Table of Contents - texnologiya.az Table of Contents About this book MySQL ... Unicode (3 questions) Import (3 questions) ... category you can easily flip through the questions contained

TableofContentsAboutthisbookMySQL(76questions)Database(44questions)InnoDB(15questions)ForeignKeys(13questions)Osx(11questions)JOIN(11questions)RubyOnRails(11questions)Performance(10questions)Select(10questions)DateTime(10questions)Mysqldump(10questions)Python(8questions)Indexing(8questions)PDO(8questions)DatabaseDesign(8questions)Types(8questions)CommandLine(7questions)Ruby(6questions)PostgreSQL(6questions)PhpMyAdmin(6questions)SqlOrderBy(6questions)PrimaryKey(6questions)SQLUPDATE(6questions)Java(5questions)Linux(5questions)Insert(5questions)MySQLWorkbench(5questions)Table(4questions)Windows(4questions)CSV(4questions)Migration(4questions)Django(4questions)Schema(4questions)GROUPBY(4questions)Date(4questions)Collation(4questions)Utf8(4questions)GreatestNPerGroup(4questions)C#(3questions)SQLServer(3questions)SQLite(3questions)

Security(3questions)String(3questions)Unicode(3questions)Import(3questions)Logging(3questions)Homebrew(3questions)Varchar(3questions)Timestamp(3questions)FullTextSearch(3questions)StoredProcedures(3questions)MysqlManagement(3questions)SQLInjection(3questions)Key(3questions)ALTERTABLE(3questions)Order(3questions)Duplicates(3questions)AutoIncrement(3questions)GroupConcat(3questions)Sqldatatypes(3questions)MysqlError1025(3questions)MysqlError1045(3questions)RubyOnRails3(3questions)JavaScript(2questions)Sockets(2questions)Arrays(2questions)Optimization(2questions)ORM(2questions)Ddl(2questions)Replace(2questions)Concatenation(2questions)Upsert(2questions)Mysql5(2questions)RowNumber(2questions)Max(2questions)CaseSensitive(2questions)BETWEEN(2questions)AmazonEC2(2questions)CompositeKey(2questions)Alter(2questions)DuplicateRemoval(2questions)WhereClause(2questions)Rank(2questions)Processlist(2questions)DeleteRow(2questions)Node.Js(2questions)MysqlError1093(2questions)

MysqlError1293(2questions)OsxYosemite(2questions)Regex(1question)GIS(1question)Math(1question)Variables(1question)Syntax(1question)Statistics(1question)Double(1question)Replication(1question)Null(1question)Multilingual(1question)Merge(1question)Configuration(1question)UUID(1question)TimeZone(1question)Conditional(1question)Monitoring(1question)JSON(1question)Caching(1question)Integer(1question)Deadlock(1question)PIVOT(1question)VirtualBox(1question)Timeout(1question)Controller(1question)Transactions(1question)PivotTable(1question)InsertId(1question)Operators(1question)InformationSchema(1question)Overhead(1question)CPUUsage(1question)CharacterEncoding(1question)Sha256(1question)AccessDenied(1question)PasswordProtection(1question)GreatCircle(1question)Deprecated(1question)UniqueKey(1question)PolymorphicAssociations(1question)UnixTimestamp(1question)MysqlError1054(1question)MariaDB(1question)MysqlError1248(1question)Doctrine2(1question)

InsertSelect(1question)INTOOUTFILE(1question)SQLINSERT(1question)MysqlError1170(1question)MysqlError1130(1question)MySQLError2006(1question)Copyright

AboutthisbookThisbookhasbeendividedintocategorieswhereeachquestionbelongstooneormorecategories.Thecategoriesarelistedbasedonhowmanyquestionstheyhave;thequestionappearsinthemostpopularcategory.Everythingislinkedinternally,sowhenbrowsingacategoryyoucaneasilyflipthroughthequestionscontainedwithinit.Wherepossiblelinkswithinquestionsandanswerslinktoappropriateplaceswithininthebook.Ifalinkdoesntlinktowithinthebook,thenitgetsaspecialicon,likethis .

http://www.example.com

MySQLSkiptoquestions,

Wikibyuserpaul-dixon

MySQL isanOpenSourcerdbms (RelationalDatabaseManagementSystem)thatrunsasaserverprovidingmulti-useraccesstoanumberofdatabases.ItssourcecodeisavailableundertheGNU (GeneralPublicLicense).

MySQL offersstandarddatabasedriverconnectivityforusingMySQLwithapplicationsandtoolsthatarecompatiblewithindustrystandardsodbc andjdbc .

Howtoaskagoodandanswerablequestion

Pleaseseethispost:TipsforaskingagoodStructuredQueryLanguage(SQL)questiontogetTipsonhowtoaskaquestionaboutMySQL-followingsomeofthosestepswillhelppeopletohelpyousolveyourproblem.

Pronunciation

Officiallyitis/maskjul/(MyS-Q-L),butisoftenpronounced/masikwl/(MySequel).

LatestVersion:5.7.11 releasedon2016-02-05.

Example

SELECT*FROMusersORDERBYName

Resources

OfficialhomepageOfficialblogMySQLDeveloperZoneMySQLdocumentationPlanetMySQLSQLFiddlePHPMySQLDocumentation

MySQLTutorials

OfficialTutorial(5.7)

Popularquestions

http://stackoverflow.com/u/6521https://www.mysql.comhttp://stackoverflow.com/questions/tagged/rdbmshttps://www.gnu.org/https://www.mysql.comhttp://stackoverflow.com/questions/tagged/odbchttp://stackoverflow.com/questions/tagged/jdbchttp://meta.stackoverflow.com/a/271056/3993662https://dev.mysql.com/doc/relnotes/mysql/5.7/en/news-5-7-11.htmlhttps://www.mysql.comhttps://blogs.oracle.com/MySQLhttps://dev.mysql.comhttps://dev.mysql.com/dochttp://planet.mysql.comhttp://sqlfiddle.comhttps://php.net/manual/en/set.mysqlinfo.phphttps://dev.mysql.com/doc/refman/5.7/en/tutorial.html

HiddenFeaturesofMySQLSQLitevsMySQLWouldyourecommendPostgreSQLoverMySQL?BestwaytopreventSQLinjectioninPHP?HowtodoaregularexpressionreplaceinMySQL?HowdoyousetadefaultvalueforaMySQLDatetimecolumn?

Popularadministrationtools

PhpMyAdminMySQLWorkbenchHeidiSQLNavicatRazorSQL

ChatRoom

StackOverflowchatroomforMySQL

Relatedtags

databasemysqlimysqldumpmysql-connectormysql2mysql5mysql-real-escape-stringmysql-managementmysql-error-1005mysql-error-1045mysql-error-1054mysql-error-1062mysql-error-1064mysql-connectmysqlldmysqlimportmysql-managementmysql-workbench

https://stackoverflow.com/questions/368858/hidden-features-of-mysqlhttps://stackoverflow.com/questions/3630/sqlite-vs-mysqlhttps://stackoverflow.com/questions/110927/do-you-recommend-postgresql-over-mysqlhttp://www.phpmyadmin.net/https://www.mysql.com/products/workbench/http://www.heidisql.com/http://www.navicat.com/http://razorsql.com/https://chat.stackoverflow.com/rooms/592/mysql-and-relational-databaseshttp://stackoverflow.com/questions/tagged/mysqlihttp://stackoverflow.com/questions/tagged/mysql-connectorhttp://stackoverflow.com/questions/tagged/mysql2http://stackoverflow.com/questions/tagged/mysql-real-escape-stringhttp://stackoverflow.com/questions/tagged/mysql-error-1005http://stackoverflow.com/questions/tagged/mysql-error-1062http://stackoverflow.com/questions/tagged/mysql-error-1064http://stackoverflow.com/questions/tagged/mysql-connecthttp://stackoverflow.com/questions/tagged/mysqlldhttp://stackoverflow.com/questions/tagged/mysqlimport

Questions

Q:HowdoIretrievemyMySQLusernameandpassword?

Tags:mysql(NextQ)

IlostmyMySQLusernameandpassword.HowdoIretrieveit?

Tags:mysql(NextQ)

User:marcel-tjandraatmadja

Answer byxenph-yan

StoptheMySQLprocess.

StarttheMySQLprocesswiththeskip-grant-tablesoption.

StarttheMySQLconsoleclientwiththe-urootoption.

Listalltheusers;SELECT*FROMmysql.user;

Resetpassword;UPDATEmysql.userSETPassword=PASSWORD('[password]')WHEREUser='[username]';

ButDONOTFORGETto

StoptheMySQLprocess

StarttheMySQLProcessnormally(i.e.withouttheskip-grant-tablesoption)

whenyouarefinished.Otherwise,yourdatabasessecuritycouldbecompromised.

Tags:mysql(NextQ)

Q:HowdoIchecktoseeifavalueisanintegerinMySQL?

Tags:mysql(PrevQ)(NextQ)

IseethatwithinMySQLthereareCast()andConvert()functionstocreateintegersfromvalues,butisthereanywaytochecktoseeifavalueisaninteger?Somethinglikeis_int()inPHPiswhatIamlookingfor.


User:craig-nakamoto

Answer byjumpy

http://stackoverflow.com/q/4371http://stackoverflow.com/u/131http://stackoverflow.com/q/4376http://stackoverflow.com/u/264http://stackoverflow.com/q/75704http://stackoverflow.com/u/8224http://stackoverflow.com/q/75880http://stackoverflow.com/u/9416

Illassumeyouwanttocheckastringvalue.OnenicewayistheREGEXPoperator,matchingthestringtoaregularexpression.SimplydoselectfieldfromtablewherefieldREGEXP'^-?[0-9]+$';

thisisreasonablyfast.Ifyourfieldisnumeric,justtestforceil(field)=field

instead.


Q:MySQLError1153-Gotapacketbiggerthanmax_allowed_packetbytes


ImimportingaMySQLdumpandgettingthefollowingerror.$mysqlfoogetMessage();}

(Ofcoursereplacedatabasename,usernameandpasswordabove)

Youcanthenquerythedatabaselikethis:$result=$db->query("select*fromtablename");foreach($resultas$row){echo$row['foo']."\n";}

Or,ifyouhavevariables:$stmt=$db->prepare("select*fromtablenamewhereid=:id");$stmt->execute(array(':id'=>42));$row=$stmt->fetch();

Ifyouneedmultipleconnectionsopenatonce,youcansimplycreatemultipleinstancesofPDO:try{$db1=newPDO('mysql:dbname=databas1;host=127.0.0.1','username','password');$db2=newPDO('mysql:dbname=databas2;host=127.0.0.1','username','password');}catch(PDOException$ex){echo'Connectionfailed:'.$ex->getMessage();}


Q:GetrecordcountsforalltablesinMySQLdatabase


IsthereawaytogetthecountofrowsinalltablesinamysqldatabasewithoutrunningaSELECTcount()oneachtable?

Cheers


User:mark

Answer byhates_SELECTSUM(TABLE_ROWS)

http://stackoverflow.com/q/275013http://stackoverflow.com/u/18180http://docs.php.net/manual/en/book.pdo.phphttp://stackoverflow.com/q/286039http://stackoverflow.com/u/37204http://stackoverflow.com/q/286048http://stackoverflow.com/u/3410

FROMINFORMATION_SCHEMA.TABLESWHERETABLE_SCHEMA='{your_db}';

Notefromthedocsthough:ForInnoDBtables,therowcountisonlyaroughestimateusedinSQLoptimization.YoullneedtouseCOUNT(*)forexactcounts(whichismoreexpensive).

Answer bygpojd

YoucanprobablyputsomethingtogetherwithTablestable .Iveneverdoneit,butitlookslikeithasacolumnfor*TABLE_ROWS*andoneforTABLENAME.

Togetrowspertable,youcanuseaquerylikethis:SELECTtable_name,table_rowsFROMINFORMATION_SCHEMA.TABLESWHERETABLE_SCHEMA='**YOURSCHEMA**';

Answer bynathan

Like@VenkatramananandothersIfoundINFORMATION_SCHEMA.TABLESunreliable(usingInnoDB,MySQL5.1.44),givingdifferentrowcountseachtimeIrunitevenonquiescedtables.Heresarelativelyhacky(butflexible/adaptable)wayofgeneratingabigSQLstatementyoucanpasteintoanewquery,withoutinstallingRubygemsandstuff.SkipcodeblockSELECTCONCAT('SELECT"',table_name,'"AStable_name,COUNT(*)ASexact_row_countFROM`',table_schema,'`.`',table_name,'`UNION')FROMINFORMATION_SCHEMA.TABLESWHEREtable_schema='**my_schema**';

Itproducesoutputlikethis:SELECT"func"AStable_name,COUNT(*)ASexact_row_countFROMmy_schema.funcUNIONSELECT"general_log"AStable_name,COUNT(*)ASexact_row_countFROMmy_schema.general_logUNIONSELECT"help_category"AStable_name,COUNT(*)ASexact_row_countFROMmy_schema.help_categoryUNIONSELECT"help_keyword"AStable_name,COUNT(*)ASexact_row_countFROMmy_schema.help_keywordUNIONSELECT"help_relation"AStable_name,COUNT(*)ASexact_row_countFROMmy_schema.help_relationUNIONSELECT"help_topic"AStable_name,COUNT(*)ASexact_row_countFROMmy_schema.help_topicUNIONSELECT"host"AStable_name,COUNT(*)ASexact_row_countFROMmy_schema.hostUNIONSELECT"ndb_binlog_index"AStable_name,COUNT(*)ASexact_row_countFROMmy_schema.ndb_binlog_indexUNION

CopyandpasteexceptforthelastUNIONtogetniceoutputlike,Skipcodeblock+------------------+-----------------+|table_name|exact_row_count|+------------------+-----------------+|func|0||general_log|0||help_category|37||help_keyword|450||help_relation|990||help_topic|504||host|0||ndb_binlog_index|0|+------------------+-----------------+

http://stackoverflow.com/q/286047http://stackoverflow.com/u/28071http://dev.mysql.com/doc/refman/5.0/en/tables-table.htmlhttp://stackoverflow.com/q/8690288http://stackoverflow.com/u/71650

8rowsinset(0.01sec)


Q:HowcanItellwhenaMySQLtablewaslastupdated?


Inthefooterofmypage,Iwouldliketoaddsomethinglikelastupdatedthexx/xx/200xwiththisdatebeingthelasttimeacertainmySQLtablehasbeenupdated.

Whatisthebestwaytodothat?Isthereafunctiontoretrievethelastupdateddate?ShouldIaccesstothedatabaseeverytimeIneedthisvalue?


User:rage

Answer byalnitak

InlaterversionsofMySQLyoucanusetheinformation_schemadatabasetotellyouwhenanothertablewasupdated:SELECTUPDATE_TIMEFROMinformation_schema.tablesWHERETABLE_SCHEMA='dbname'ANDTABLE_NAME='tabname'

Thisdoesofcoursemeanopeningaconnectiontothedatabase.

AnalternativeoptionwouldbetotouchaparticularfilewhenevertheMySQLtableisupdated:

Ondatabaseupdates:

OpenyourtimestampfileinO_RDRWmodecloseitagain

oralternatively

usetouch() ,thePHPequivalentoftheutimes()function,tochangethefiletimestamp.

Onpagedisplay:

usestat()toreadbackthefilemodificationtime.


Q:MySQL/SQL:GroupbydateonlyonaDatetimecolumn


Havingatablewithacolumnlike:mydateDATETIME

http://stackoverflow.com/q/307438http://stackoverflow.com/u/39474http://stackoverflow.com/q/307488http://stackoverflow.com/u/6782http://us3.php.net/manual/en/function.touch.phphttp://stackoverflow.com/q/366603

Ihaveaquerysuchas:SELECTSUM(foo),mydateFROMa_tableGROUPBYa_table.mydate;

Thiswillgroupbythefulldatetime,includinghoursandminutes.Iwishtomakethegroupby,onlybythedateYYYY/MM/DDnotbytheYYYY/MM/DD/HH/mm.

Anyoneknowhowtodothis?Icanstilldoit(asIamatm),dynamicallyinmycode,butImcleaningtrashcodeandthiscanbemadethroughtheSQLIjustcantfindouthow:(.


User:fmsf

Answer bymichael-haren

Castthedatetimetoadate,thenGROUPBYusingthissyntax:SELECTSUM(foo),DATE(mydate)FROMa_tableGROUPBYDATE(a_table.mydate);

OryoucanGROUPBYthealiasas@orlandu63suggested:SELECTSUM(foo),DATE(mydate)DateOnlyFROMa_tableGROUPBYDateOnly;

ThoughIdontthinkitllmakeanydifferencetoperformance,itisalittleclearer.


Q:SQL-findrecordsfromonetablewhichdontexistinanother


IvegotthefollowingtwoSQLtables(inMySQL):SkipcodeblockPhone_book+----+------+--------------+|id|name|phone_number|+----+------+--------------+|1|John|111111111111|+----+------+--------------+|2|Jane|222222222222|+----+------+--------------+

Call+----+------+--------------+|id|date|phone_number|+----+------+--------------+|1|0945|111111111111|+----+------+--------------+|2|0950|222222222222|+----+------+--------------+|3|1045|333333333333|+----+------+--------------+

HowdoIfindoutwhichcallsweremadebypeoplewhosephone_numberisnotinthePhone_book?Thedesiredoutputwouldbe:Call+----+------+--------------+|id|date|phone_number|+----+------+--------------+

http://stackoverflow.com/u/26004http://stackoverflow.com/q/366610http://stackoverflow.com/u/29http://stackoverflow.com/q/367863

|3|1045|333333333333|+----+------+--------------+

Anyhelpwouldbemuchappreciated.


User:philip-morton

Answer byalnitak

Theresseveraldifferentwaysofdoingthis,withvaryingefficiency,dependingonhowgoodyourqueryoptimiseris,andtherelativesizeofyourtwotables:

Thisistheshorteststatement,andmaybequickestifyourphonebookisveryshort:SELECT*FROMCallWHEREphone_numberNOTIN(SELECTphone_numberFROMPhone_book)

alternatively(thankstoAlterlife )SELECT*FROMCallWHERENOTEXISTS(SELECT*FROMPhone_bookWHEREPhone_book.phone_number=Call.phone_number)

or(thankstoKieran )SELECT*FROMCallLEFTOUTERJOINPhone_BookON(Call.phone_number=Phone_book.phone_number)WHEREPhone_book.phone_numberISNULL

(ignoringthat,asothershavesaid,itsnormallybesttoselectjustthecolumnsyouwant,not*)

Answer bywoprSELECTCall.ID,Call.date,Call.phone_numberFROMCallLEFTOUTERJOINPhone_BookON(Call.phone_number=Phone_book.phone_number)WHEREPhone_book.phone_numberISNULL

Shouldremovethesubquery,allowingthequeryoptimisertoworkitsmagic.

Also,avoidSELECT*becauseitcanbreakyourcodeifsomeonealterstheunderlyingtablesorviews(anditsinefficient).


Q:MySQLvsMySQLiwhenusingPHP


Whichisbetter,MySQLorMySQLi?Andwhy?WhichshouldIuse?

http://stackoverflow.com/u/21709http://stackoverflow.com/q/367865http://stackoverflow.com/u/6782http://stackoverflow.com/users/36848/alterlifehttp://stackoverflow.com/users/46255/kieranhttp://stackoverflow.com/q/368123http://stackoverflow.com/u/46255http://stackoverflow.com/q/548986

Imeanbetternotjustintermsofperformance,butanyotherrelevantfeature.


User:anand.trex

Answer bymark-davidson

IfyouhavealookatMySQLImprovedExtensionOverview ,itshouldtellyoueverythingyouneedtoknowaboutthedifferencesbetweenthetwo.

Themainusefulfeaturesare:

anObject-orientedinterfacesupportforpreparedstatementssupportformultiplestatementssupportfortransactionsenhanceddebuggingcapabilitiesembeddedserversupport.

Answer bygordon

Thereisamanualpagededicatedtohelpchoosingbetweenmysql,mysqliandPDOat

http://php.net/manual/en/mysqlinfo.api.choosing.php andhttp://www.php.net/manual/en/mysqlinfo.library.choosing.php

ThePHPteamrecommendsmysqliorPDO_MySQLfornewdevelopment:

ItisrecommendedtouseeitherthemysqliorPDO_MySQLextensions.Itisnotrecommendedtousetheoldmysqlextensionfornewdevelopment.Adetailedfeaturecomparisonmatrixisprovidedbelow.Theoverallperformanceofallthreeextensionsisconsideredtobeaboutthesame.AlthoughtheperformanceoftheextensioncontributesonlyafractionofthetotalruntimeofaPHPwebrequest.Often,theimpactisaslowas0.1%.

ThepagealsohasafeaturematrixcomparingtheextensionAPIs.ThemaindifferencesbetweenmysqliandmysqlAPIareasfollows:SkipcodeblockmysqlimysqlDevelopmentStatusActiveMaintenanceonlyLifecycleActiveLongTermDeprecationAnnounced*RecommendedYesNoOOPAPIYesNoAsynchronousQueriesYesNoServer-SidePrep.StatementsYesNoStoredProceduresYesNoMultipleStatementsYesNoTransactionsYesNoMySQL5.1+functionalityYesNo

*http://news.php.net/php.internals/53799

Thereisanadditionalfeaturematrixcomparingthelibraries(newmysqlndversus

http://stackoverflow.com/u/12649http://stackoverflow.com/q/549000http://stackoverflow.com/u/50866http://php.net/manual/en/mysqli.overview.phphttp://stackoverflow.com/q/8891836http://stackoverflow.com/u/208809http://php.net/manual/en/mysqlinfo.api.choosing.phphttp://www.php.net/manual/en/mysqlinfo.library.choosing.phphttp://news.php.net/php.internals/53799

libmysql)at

http://www.php.net/manual/en/mysqlinfo.library.choosing.php

andaverythoroughblogarticleat

http://blog.ulf-wendel.de/2012/php-mysql-why-to-upgrade-extmysql/


Q:Searchforalloccurrencesofastringinamysqldatabase


Imtryingtofigureouthowtolocatealloccurrencesofaurlinadatabase.Iwanttosearchalltablesandallfields.ButIhavenoideawheretostartorifitsevenpossible.


User:gregh

Answer bypaolo-bergantino

Asimplesolutionwouldbedoingsomethinglikethis:mysqldump-umyuser--no-create-infodatabasename>myfile.sql

Thenyoucanjustdoafindonmyfile.sqlfortheURLyouwant.

Answer bya.-googler

OldpostIknow,butforothersthatfindthisviaGooglelikeIdid,ifyouhavephpmyadmininstalled,ithasaglobalsearchfeature.


Q:Add2hourstocurrenttimeinMySQL?


WhichisthevalidsyntaxofthisqueryinMySQL?SELECT*FROMcoursesWHERE(now()+2hours)>start_time

*note:start_timeisafieldofcoursestable*


User:ei-maung

Answer byglavi

http://www.php.net/manual/en/mysqlinfo.library.choosing.phphttp://blog.ulf-wendel.de/2012/php-mysql-why-to-upgrade-extmysql/http://stackoverflow.com/q/562457http://stackoverflow.com/u/2687http://stackoverflow.com/q/562501http://stackoverflow.com/u/16417http://stackoverflow.com/q/7392555http://stackoverflow.com/u/941177http://stackoverflow.com/q/589652http://stackoverflow.com/u/22962http://stackoverflow.com/q/589668http://stackoverflow.com/u/67332

SELECT*FROMcoursesWHEREDATE_ADD(NOW(),INTERVAL2HOUR)>start_time

SeeDateandTimeFunctions forotherdate/timemanipulation.


Q:SearchinallfieldsfromeverytableofaMySQLdatabase


IwanttosearchinallfieldsfromalltablesofaMySQLdatabaseagivenstring,possiblyusingsyntaxas:SELECT*FROM*WHERE*LIKE'%stuff%'

Isitpossibletodosomethinglikethis?


User:rsilva

Answer bymilhous

Youcanpeekintotheinformation_schematable.Ithasalistofalltablesandallfieldsthatareinatable.Youcanthenrunqueriesusingtheinformationthatyouhavegottenfromthistable.

Answer bydean-rather

YoucoulddoanSQLDumpofthedatabase(anditsdata)thensearchthatfile.

Answer bygreg-lyon

IfyouhavephpMyAdmininstalleduseitsSearchfeature.

SelectyourDBBesureyoudohaveaDBselected(i.e.notatable,otherwiseyoullgetacompletelydifferentsearchdialog)ClickSearchtabChoosethesearchtermyouwantChoosethetablestosearch

Ihaveusedthisonupto250table/10GBdatabases(onafastserver)andtheresponsetimeisnothingshortofamazing.


Q:DeletewithJoininMySQL

http://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.htmlhttp://stackoverflow.com/q/639531http://stackoverflow.com/u/2019426http://stackoverflow.com/q/639538http://stackoverflow.com/u/17712http://stackoverflow.com/q/4817152http://stackoverflow.com/u/14966http://stackoverflow.com/q/3841554http://stackoverflow.com/u/179289http://stackoverflow.com/q/652770

Tags:mysql(PrevQ)(NextQ)SkipcodeblockCREATETABLE`clients`(`client_idìnt(11),PRIMARYKEY(`client_id`));CREATETABLE`projects`(`project_idìnt(11)unsigned,`client_idìnt(11)unsigned,PRIMARYKEY(`project_id`));CREATETABLE`posts`(`post_idìnt(11)unsigned,`project_idìnt(11)unsigned,PRIMARYKEY(`post_id`));

InmyPHPcode,whendeletingaclient,Iwanttodeleteallprojectsposts:DELETEFROMposts

INNERJOINprojectsONprojects.project_id=posts.project_id

WHEREprojects.client_id=:client_id;

Thepoststabledoesnothaveaforeignkeyclient_id,onlyproject_id.Iwanttodeletepoststhatarepostedinprojectsthathavethepassedclient_id.

Thisisnotworkingrightnow(nopostsaredeleted).


User:geekjock

Answer byyehosef

Youjustneedtospecifythatyouwanttodeletetheentriesfromthepoststable:DELETEpostsFROMpostsINNERJOINprojectsONprojects.project_id=posts.project_idWHEREprojects.client_id=:client_id

EDIT:Formoreinformationyoucanseethisalternativeanswer


Q:FindingduplicatevaluesinMySQL


Ihaveatablewithavarcharcolumn,andIwouldliketofindalltherecordsthathaveduplicatevaluesinthiscolumn.WhatisthebestqueryIcanusetofindtheduplicates?


User:jon-tackabury

http://stackoverflow.com/u/74980http://stackoverflow.com/q/4192849http://stackoverflow.com/u/214545http://stackoverflow.com/a/29204958/214545http://stackoverflow.com/q/688549http://stackoverflow.com/u/343

Answer bylevik

DoaSELECTwithaGROUPBYclause.Letssaynameisthecolumnyouwanttofindduplicatesin:SELECTname,COUNT(*)cFROMtableGROUPBYnameHAVINGc>1;

Thiswillreturnaresultwiththenamevalueinthefirstcolumn,andacountofhowmanytimesthatvalueappearsinthesecond.

Answer bymaxyfcSELECTvarchar_colFROMtableGROUPBYvarchar_colHAVINGcount(*)>1;

Answer byquassnoiSELECT*FROMmytablemtoWHEREEXISTS(SELECT1FROMmytablemtiWHEREmti.varchar_column=mto.varchar_columnLIMIT1,1)

Thisqueryreturnscompleterecords,notjustdistinctvarchar_columns.

ThisquerydoesntuseCOUNT(*).Iftherearelotsofduplicates,COUNT(*)isexpensive,andyoudontneedthewholeCOUNT(*),youjustneedtoknowiftherearetworowswithsamevalue.

Havinganindexonvarchar_columnwill,ofcourse,speedupthisquerygreatly.


Q:PHP/MySQLinsertrowthengetid


TheidfieldofmytableautoincreaseswhenIinsertarow.IwanttoinsertarowandthengetthatID.

IwoulddoitjustasIsaidit,butisthereawayIcandoitwithoutworryingaboutthetimebetweeninsertingtherowandgettingtheid?

IknowIcanquerythedatabasefortherowthatmatchestheinformationthatwasentered,butthereisahighchangetherewillbeduplicates,withtheonlydifferencebeingtheid.


User:hintswen

Answer bycletus

http://stackoverflow.com/q/688551http://stackoverflow.com/u/4465http://stackoverflow.com/q/688560http://stackoverflow.com/u/72990http://stackoverflow.com/q/689294http://stackoverflow.com/u/55159http://stackoverflow.com/q/897356http://stackoverflow.com/u/51310http://stackoverflow.com/q/897361http://stackoverflow.com/u/18393

mysqli_query("INSERTINTOmytable(1,2,3,'blah')");$id=mysqli_insert_id();

Seemysqli_insert_id() .

Whateveryoudo,dontinsertandthendoaSELECTMAX(id)FROMmytable.Likeyousay,itsaraceconditionandtheresnoneed.mysqli_insert_id()alreadyhasthisfunctionality.


Q:HowtogetdatabasestructureinMySQLviaquery


IsitpossibletosomehowgetstructureofMySQLdatabase,orjustsometablewithsimplequery?

Oristhereanotherway,howcanIdoit?


User:jakub-arnold

Answer bybill-the-lizard

IthinkthatwhatyoureafterisDESCRIBEDESCRIBEtable;

YoucanalsouseSHOWTABLESSHOWTABLES;

togetalistofthetablesinyourdatabase.

Answer byeemeli-kantola

TogetthewholedatabasestructureasasetofCREATETABLE statements,usemysqldump :mysqldumpdatabase_name--compact--no-data

Forsingletables,addthetablenameafterdbnameinmysqldump.YougetthesameresultswithSQLandSHOWCREATETABLE :SHOWCREATETABLEtable;

OrDESCRIBE ifyoupreferacolumnlisting:DESCRIBEtable;


http://au.php.net/mysqli.insert_idhttp://stackoverflow.com/q/898688http://stackoverflow.com/u/72583http://stackoverflow.com/q/898710http://stackoverflow.com/u/1288http://dev.mysql.com/doc/refman/4.1/en/describe.htmlhttps://dev.mysql.com/doc/refman/5.0/en/show-tables.htmlhttp://stackoverflow.com/q/899139http://stackoverflow.com/u/94956http://dev.mysql.com/doc/refman/5.1/en/create-table.htmlhttp://dev.mysql.com/doc/refman/5.1/en/mysqldump.htmlhttp://dev.mysql.com/doc/refman/5.1/en/show-create-table.htmlhttp://dev.mysql.com/doc/refman/5.1/en/describe.html

Q:WhatdoestheKEYkeywordmean?


Inthistabledefinition:CREATETABLEgroups(ug_main_grp_idsmallintNOTNULLdefault'0',ug_uidsmallintdefaultNULL,ug_grp_idsmallintdefaultNULL,KEY(ug_main_grp_id));

WhatdoestheKEYkeywordmean?Itsnotaprimarykey,itsnotaforiegnkey,soisitjustanindex?Ifso,whatssospecialaboutthistypeofindexcreatedwithKEY?


User:stan

Answer bymartinodf

Quotingfromhttp://dev.mysql.com/doc/refman/5.1/en/create-table.html{INDEX|KEY}

SoKEYisanINDEX;)


Q:Changeautoincrementstartingnumber?


InMySQL,Ihaveatable,andIwanttosetthestart?auto_incrementvalueto5,not1.Isthispossibleandwhatquerystatementdoesthis?


User:john-jones

Answer bydaniel-vandersluis

YoucanuseALTERTABLEtochangetheauto_incrementinitialvalue:ALTERTABLEtblAUTO_INCREMENT=5;

SeetheMySQLreference formoredetails.

Answer bycosimo

Yes,youcanusetheALTERTABLEtAUTO_INCREMENT=42statement.However,youneedtobeawarethatthiswillcausetherebuildingofyourentiretable,atleastwithInnoDB.Ifyouhaveanalreadyexistingdatasetwithmillionsofrows,itcouldtakeaverylongtimetocomplete.

http://stackoverflow.com/q/924265http://stackoverflow.com/q/924272http://stackoverflow.com/u/112870http://dev.mysql.com/doc/refman/5.1/en/create-table.htmlhttp://stackoverflow.com/q/970597http://stackoverflow.com/u/119894http://stackoverflow.com/q/970652http://stackoverflow.com/u/92313http://dev.mysql.com/doc/refman/5.0/en/example-auto-increment.htmlhttp://stackoverflow.com/q/12401149http://stackoverflow.com/u/11303

Inmyexperience,itsbettertodothefollowing:BEGINWORK;YoumayalsoneedtoaddothermandatorycolumnsandvaluesINSERTINTOt(id)VALUES(42);ROLLBACK;

Inthisway,evenifyourerollingbackthetransaction,MySQLwillkeeptheauto-incrementvalue,andthechangewillbeappliedinstantly.

YoucanverifythisbyissuingaSHOWCREATETABLEtstatement.Youshouldsee:>SHOWCREATETABLEt\G***************************1.row***************************Table:tCreateTable:CREATETABLE`t`(...)ENGINE=InnoDBAUTO_INCREMENT=43


Q:HowdoIremoveaMySQLdatabase?


Youmaynoticefrommylastquestionthataproblemcausedsomemoreproblems,ReadingMySQLmanualsinMySQLmonitor?

Mydatabaseisnowunusablepartlyduetomyinteresttobreakthingsandmyinabilitytolookaterrormessages.IknowthatIshouldnotreuseprimarykeys,butIwouldliketousethemagainaftertheremovalofthedatabasethatIdeteriorated.So

HowcanIcorrectlyremoveaMySQLdatabase?


User:masi

Answer byrnicholson

FromtheMySQLprompt:mysql>DROPDATABASE;


Q:MySQLLIKEIN()?


Mycurrentquerylookslikethis:SELECT*FROMfiberboxfWHEREf.fiberBoxLIKE'%1740%'ORf.fiberBoxLIKE'%1938%'ORf.fiberBoxLIKE'%1940%'

IdidsomelookingaroundandcantfindanythingsimilartoaLIKEIN()-Ienvisionitworkinglikethis:

http://stackoverflow.com/q/1082130http://stackoverflow.com/questions/1081399http://stackoverflow.com/u/54964http://stackoverflow.com/q/1082136http://stackoverflow.com/u/14075http://stackoverflow.com/q/1127088

SELECT*FROMfiberboxfWHEREf.fiberboxLIKEIN('%140%','%1938%','%1940%')

Anyideas?AmIjustthinkingoftheproblemthewrongway-someobscurecommandIveneverseen.

MySQL5.0.77-community-log


User:michael-wales

Answer bypaul-dixon

AREGEXP mightbemoreefficient,butyoudhavetobenchmarkittobesure,e.g.SELECT*fromfiberboxwherefieldREGEXP'1740|1938|1940';

Answer bydavid-carroll

PaulDixonsanswerworkedbrilliantlyforme.Toaddtothis,herearesomethingsIobservedforthoseinterestedinusingREGEXP:

ToAccomplishmultipleLIKEfilterswithWildcards:SELECT*FROMfiberboxWHEREfieldLIKE'%1740%'ORfieldLIKE'%1938%'ORfieldLIKE'%1940%';

UseREGEXPAlternative:SELECT*FROMfiberboxWHEREfieldREGEXP'1740|1938|1940';

ValueswithinREGEXPquotesandbetweenthe|(OR)operatoraretreatedaswildcards.Typically,REGEXPwillrequirewildcardexpressionssuchas(.*)1740(.*)toworkas%1740%.

Ifyouneedmorecontroloverplacementofthewildcard,usesomeofthesevariants:

ToAccomplishLIKEwithControlledWildcardPlacement:SELECT*FROMfiberboxWHEREfieldLIKE'1740%'ORfieldLIKE'%1938'ORfieldLIKE'%1940%test';

Use:SELECT*FROMfiberboxWHEREfieldREGEXP'^1740|1938$|1940(.*)test';

Placing^infrontofthevalueindicatesstartoftheline.

Placing$afterthevalueindicatesendofline.

Placing(.*)behavesmuchlikethe%wildcard.

The.indicatesanysinglecharacter,exceptlinebreaks.Placing.inside()with*(.*)addsarepeatingpatternindicatinganynumberofcharacterstillendofline.

Therearemoreefficientwaystonarrowdownspecificmatches,butthatrequiresmorereviewofRegularExpressions.NOTE:NotallregexpatternsappeartoworkinMySQL

http://stackoverflow.com/u/2001511http://stackoverflow.com/q/1127106http://stackoverflow.com/u/6521http://dev.mysql.com/doc/refman/5.1/en/regexp.htmlhttp://stackoverflow.com/q/4808757http://stackoverflow.com/u/591080

statements.Youllneedtotestyourpatternsandseewhatworks.

Finally,ToAccomplishMultipleLIKEandNOTLIKEfilters:SELECT*FROMfiberboxWHEREfieldLIKE'%1740%'ORfieldLIKE'%1938%'ORfieldNOTLIKE'%1940%'ORfieldNOTLIKE'test%'ORfield='9999';

UseREGEXPAlternative:SELECT*FROMfiberboxWHEREfieldREGEXP'1740|1938|^9999$'ORfieldNOTREGEXP'1940|^test';

ORMixedAlternative:SELECT*FROMfiberboxWHEREfieldREGEXP'1740|1938'ORfieldNOTREGEXP'1940|^test'ORfieldNOTLIKE'test%'ORfield='9999';

NoticeIseparatedtheNOTsetinaseparateWHEREfilter.Iexperimentedwithusingnegatingpatterns,forwardlookingpatterns,andsoon.However,theseexpressionsdidnotappeartoyieldthedesiredresults.Inthefirstexampleabove,Iuse^9999$toindicateexactmatch.Thisallowsyoutoaddspecificmatcheswithwildcardmatchesinthesameexpression.However,youcanalsomixthesetypesofstatementsasyoucanseeinthesecondexamplelisted.

Regardingperformance,Iransomeminortestsagainstanexistingtableandfoundnodifferencesbetweenmyvariations.However,Iimagineperformancecouldbeanissuewithbiggerdatabases,largerfields,greaterrecordcounts,andmorecomplexfilters.

Asalways,uselogicaboveasitmakessense.

Ifyouwanttolearnmoreaboutregularexpressions,Irecommendwww.regular-expressions.infoasagoodreferencesite.


Q:MySQL,bettertoinsertNULLoremptystring?


Ihaveaformonawebsitewhichhasalotofdifferentfields.Someofthefieldsareoptionalwhilesomearemandatory.InmyDBIhaveatablewhichholdsallthesevalues,isitbetterpracticetoinsertaNULLvalueoranemptystringintotheDBcolumnswheretheuserdidntputanydata?


User:roflwaffle

Answer byquassnoi

ByusingNULLyoucandistinguishbetweenputnodataandputemptydata.

http://stackoverflow.com/q/1267999http://stackoverflow.com/u/49887http://stackoverflow.com/q/1268017http://stackoverflow.com/u/55159

Somemoredifferences:

ALENGTHofNULLisNULL,aLENGTHofanemptystringis0.

NULLsaresortedbeforetheemptystrings.

COUNT(message)willcountemptystringsbutnotNULLs

YoucansearchforanemptystringusingaboundvariablebutnotforaNULL.Thisquery:SELECT*FROMmytableWHEREmytext=?

willnevermatchaNULLinmytext,whatevervalueyoupassfromtheclient.TomatchNULLs,youllhavetouseotherquery:SELECT*FROMmytableWHEREmytextISNULL


Q:MySQL:Countoccurrencesofdistinctvalues


IamtryingtofindaMySQLquerythatwillfinddistinctvaluesinaparticularfield,countthenumberofoccurrencesofthatvalueandthenordertheresultsbythecount.

exampledbidname-----------1Mark2Mike3Paul4Mike5Mike6John7Mark

expectedresultnamecount----------Mike3Mark2Paul1John1

Thanks


User:jimmyj

Answer byamberSELECTname,COUNT(*)ascountFROMtablenameGROUPBYnameORDERBYcountDESC;

http://stackoverflow.com/q/1346345http://stackoverflow.com/u/2083http://stackoverflow.com/q/1346352http://stackoverflow.com/u/148870


Q:HowdoIchangethedatatypeforacolumninMySQL?


Iwanttochangethedatatypeofmultiplecolumnsfromfloattoint.Whatisthesimplestwaytodothis?

Thereisnodatatoworryabout,yet.


User:eric-wilson

Answer byyannick-motton

http://dev.mysql.com/doc/refman/5.1/en/alter-table.htmlALTERTABLEtablenameMODIFYcolumnnameINTEGER;

Thiswillchangethedatatypeofgivencolumn

Dependingonhowmanycolumnsyouwishtomodifyitmightbebesttogenerateascript,orusesomekindofmysqlclientGUI


Q:HowtogetIDofthelastupdatedrowinMySQL?


HowdoIgettheIDofthelastupdatedrowinMySQLusingPHP?


User:avinash

Answer bypomyk

Ivefoundananswertothisproblem:)SET@update_id:=0;UPDATEsome_tableSETcolumn_name='value',id=(SELECT@update_id:=id)WHEREsome_other_column='blah'LIMIT1;SELECT@update_id;

EDITbyaefxx

ThistechniquecanbefurtherexpandedtoretrievetheIDofeveryrowaffectedbyanupdatestatement:SET@uids:=null;UPDATEfootableSETfoo='bar'

http://stackoverflow.com/q/1356866http://stackoverflow.com/u/82474http://stackoverflow.com/q/1356875http://stackoverflow.com/u/68822http://dev.mysql.com/doc/refman/5.1/en/alter-table.htmlhttp://stackoverflow.com/q/1388025http://stackoverflow.com/u/148478http://stackoverflow.com/q/1751282http://stackoverflow.com/u/169213

WHEREfooid>5AND(SELECT@uids:=CONCAT_WS(',',fooid,@uids));SELECT@uids;

ThiswillreturnastringwithalltheIDsconcatenatedbyacolon.


Q:Howtogetnext/previousrecordinMySQL?


SayIhaverecordswithIDs3,4,7,9andIwanttobeabletogofromonetoanotherbynavitagionvianext/previouslinks.Theproblemis,thatIdontknowhowtofetchrecordwithnearesthigherID.

SowhenIhaverecordwithID4,Ineedtobeabletofetchnextexistingrecord,whichwouldbe7.ThequerywouldprobablylooksomethinglikeSELECT*FROMfooWHEREid=4OFFSET1

HowcanIfetchnext/previousrecordwithoutfetchingwholeresultsetandmanualyiterating?

ImusingMySQL5.


User:jakub-arnold

Answer bylongneck

next:select*fromfoowhereid=(selectmin(id)fromfoowhereid>4)

previous:select*fromfoowhereid=(selectmax(id)fromfoowhereid4ORDERBYidLIMIT1;

previousrecord:SELECT*FROMfooWHEREidmytagfieldissettoUNIQUEandIsimplywantthedatabasetoignoreanyduplicatetag.INSERTINTOtable_tags(tag)VALUES('tag_a'),('tab_b'),('tag_c')ONDUPLICATEKEYIGNORE'*theoffendingtagandcarryon*'

oreventhiswouldbeacceptableINSERTINTOtable_tags(tag)VALUES('tag_a'),('tab_b'),('tag_c')ONDUPLICATEKEYUPDATE'*theoffendingtagandcarryon*'


User:good-bye

Answer bythummper

WouldsuggestNOTusingINSERTIGNOREasitignoresALLerrors(ieitsasloppyglobalignore).Instead,sinceinyourexampletagistheuniquekey,use:INSERTINTOtable_tags(tag)VALUES('tag_a'),('tab_b'),('tag_c')ONDUPLICATEKEYUPDATEtag=tag;

onduplicatekeyproduces:

http://stackoverflow.com/u/263960http://stackoverflow.com/q/2215359http://stackoverflow.com/u/21441http://stackoverflow.com/q/2215360http://stackoverflow.com/u/45531http://www.php.net/manual/en/function.date.php#85692http://stackoverflow.com/q/2366813http://stackoverflow.com/u/195192http://stackoverflow.com/q/4920619http://stackoverflow.com/u/606330

QueryOK,0rowsaffected(0.07sec)


Q:MySQLqueryStringcontains


IvebeentryingtofigureouthowIcanmakeaquerywithMySQLthatchecksifthevalue(string$haystack)inacertaincolumncontainscertaindata(string$needle),likethis:mysql_query("SELECT*FROM`table`WHERE`column`.contains('{$needle}')");

InPHP,thefunctioniscalledsubstr($haystack,$needle),somaybe:WHEREsubstr(`column`,'{$needle}')=1


User:arik

Answer bywolph

Quitesimpleactually:mysql_query("SELECT*FROM`table`WHERE`column`LIKE'%{$needle}%'");

The%isawildcardforanycharacter.Donotethatthiscangetslowonverylargedatasetssoifyourdatabasegrowsyoullneedtousefulltextindices.

Answer byomg-ponies

Use:SELECT*FROM`table`WHEREINSTR(`column`,'{$needle}')>0

Reference:

INSTR


Q:MySQL:Howtocopyrows,butchangeafewfields?

http://stackoverflow.com/q/2602252http://stackoverflow.com/u/299711http://stackoverflow.com/q/2602274http://stackoverflow.com/u/54017http://stackoverflow.com/q/2602280http://stackoverflow.com/u/135152http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_instrhttp://stackoverflow.com/q/2783150


IhavealargenumberofrowsthatIwouldliketocopy,butIneedtochangeonefield.

IcanselecttherowsthatIwanttocopy:select*fromTablewhereEvent_ID="120"

NowIwanttocopyallthoserowsandcreatenewrowswhilesettingtheEvent_IDto155.HowcanIaccomplishthis?


User:andrew

Answer bydcpINSERTINTOTable(Event_ID,col2...)SELECT"155",col2...FROMTableWHEREEvent_ID="120"

Here,thecol2,representtheremainingcolumns(theonesotherthanEvent_ID)inyourtable.

Answer byalex-christodoulou

Thisisasolutionwhereyouhavemanyfieldsinyourtableanddontwanttogetafingercrampfromtypingallthefields,justtypetheonesneeded:)

Howtocopysomerowsintothesametable,withsomefieldshavingdifferentvalues:

1. Createatemporarytablewithalltherowsyouwanttocopy2. Updatealltherowsinthetemporarytablewiththevaluesyouwant3. Ifyouhaveanautoincrementfield,youshouldsetittoNULLinthetemporarytable4. Copyalltherowsofthetemporarytableintoyouroriginaltable5. Deletethetemporarytable

Yourcode:CREATEtabletemporary_tableASSELECT*FROMoriginal_tableWHEREEvent_ID="155";

UPDATEtemporary_tableSETEvent_ID="120";

UPDATEtemporary_tableSETID=NULL

INSERTINTOoriginal_tableSELECT*FROMtemporary_table;

DROPTABLEtemporary_table

Generalscenariocode:CREATEtabletemporary_tableASSELECT*FROMoriginal_tableWHERE;

UPDATEtemporary_tableSET=,=,...;

UPDATEtemporary_tableSET=NULL;

http://stackoverflow.com/u/48523http://stackoverflow.com/q/2783162http://stackoverflow.com/u/109360http://stackoverflow.com/q/15344327http://stackoverflow.com/u/1611330


DROPTABLEtemporary_table

Simplified/condensedcode:CREATETEMPORARYTABLEtemporary_tableASSELECT*FROMoriginal_tableWHERE;

UPDATEtemporary_tableSET=NULL,=,=,...;


AscreationofthetemporarytableusestheTEMPORARYkeyworditwillbedroppedautomaticallywhenthesessionfinishes(as@ar34zsuggested).


Q:caseinsensitiveforsqlLIKEwildcardstatement


Sorryifthisisarepeat.IlookedaroundsomeanddidntfindwhatIwasaftersoheregoes.SELECT*FROMtreesWHEREtrees.`title`LIKE'%elm%'

Thisworksfine,butnotifthetreeisnamedElmorELMectHowdoImakeSQLcaseinsensitiveforthiswild-cardsearch?

Again,apologiesifthisisrepeated.

Oh,usingMySql5onapache.


User:david-morrow

Answer byquassnoiSELECT*FROMtreesWHEREtrees.`title`COLLATEUTF8_GENERAL_CILIKE'%elm%'

Answer bycwallenpoole

Ivealwayssolvedthisusinglower:SELECT*FROMtreesWHERELOWER(trees.title)LIKE'%elm%'


Q:mysql_fetch_array()/mysql_fetch_assoc()/mysql_fetch_row()expectsparameter1toberesourceormysqli_result,booleangiven

http://stackoverflow.com/q/2876789http://stackoverflow.com/u/279558http://stackoverflow.com/q/2876820http://stackoverflow.com/u/55159http://stackoverflow.com/q/2876802http://stackoverflow.com/u/57191http://stackoverflow.com/q/2973202


IamtryingtoselectdatafromaMySQLtable,butIgetoneofthefollowingerrormessages:

mysql_fetch_array()expectsparameter1toberesource,booleangiven

or

mysqli_fetch_array()expectsparameter1tobemysqli_result,booleangiven

Thisismycode:$username=$_POST['username'];$password=$_POST['password'];

$result=mysql_query('SELECT*FROMUsersWHEREUserNameLIKE$username');

while($row=mysql_fetch_array($result)){echo$row['FirstName'];}

Thesameappliestocodelike$result=mysqli_query($mysqli,'SLECT');//mysqli_fetch_array()expectsparameter1tobemysqli_result,booleangivenwhile($row=mysqli_fetch_array($result)){...

and$result=$mysqli->query($mysqli,'SELCT');//Calltoamemberfunctionfetch_assoc()onanon-objectwhile($row=$result->fetch_assoc($result)){...

and$result=$pdo->query('SLECT',PDO::FETCH_ASSOC);//Invalidargumentsuppliedforforeach()foreach($resultas$row){...

and$stmt=$mysqli->prepare('SLECT');//Calltoamemberfunctionbind_param()onanon-object$stmt->bind_param(...)

and$stmt=$pdo->prepare('SLECT');//CalltoamemberfunctionbindParam()onanon-object$stmt->bindParam(...)


User:iamjonesy

Answer byscompt.com

Aquerymayfailforvariousreasonsinwhichcaseboththemysql_*andthemysqliextensionwillreturnfalsefromtheirrespectivequeryfunctions/methods.Youneedto

http://stackoverflow.com/u/299871http://stackoverflow.com/q/2973209http://stackoverflow.com/u/111777

testforthaterrorconditionandhandleitaccordingly.

mysql_*extension :

NOTEThemysql_functionsaredeprecatedandwillberemovedwiththeupcomingphpversion7.

Check$resultbeforepassingittomysql_fetch_array.Youllfindthatitsfalsebecausethequeryfailed.Seethemysql_query documentationforpossiblereturnvaluesandsuggestionsforhowtodealwiththem.Skipcodeblock$username=mysql_real_escape_string($_POST['username']);$password=$_POST['password'];$result=mysql_query("SELECT*FROMUsersWHEREUserNameLIKE'$username'");

if($result===FALSE){die(mysql_error());//TODO:bettererrorhandling}

while($row=mysql_fetch_array($result)){echo$row['FirstName'];}

mysqliextensionproceduralstyle:Skipcodeblock$username=mysqli_real_escape_string($mysqli,$_POST['username']);$result=mysqli_query($mysqli,"SELECT*FROMUsersWHEREUserNameLIKE'$username'");

//mysqli_queryreturnsfalseifsomethingwentwrongwiththequeryif($result===FALSE){yourErrorHandler(mysqli_error($mysqli));}else{//asofphp5.4mysqli_resultimplementsTraversable,soyoucanuseitwithforeachforeach($resultas$row){...

oo-style:Skipcodeblock$username=$mysqli->escape_string($_POST['username']);$result=$mysqli->query("SELECT*FROMUsersWHEREUserNameLIKE'$username'");

if($result===FALSE){yourErrorHandler($mysqli->error);//or$mysqli->error_list}else{//asofphp5.4mysqli_resultimplementsTraversable,soyoucanuseitwithforeachforeach($resultas$row){...

usingapreparedstatement:Skipcodeblock$stmt=$mysqli->prepare('SELECT*FROMUsersWHEREUserNameLIKE?');if(!$stmt){yourErrorHandler($mysqli->error);//or$mysqli->error_list}elseif(!$stmt->bind_param('s',$_POST['username'])){yourErrorHandler($stmt->error);//or$stmt->error_list}elseif(!$stmt->execute()){yourErrorHandler($stmt->error);//or$stmt->error_list

http://docs.php.net/book.mysqlhttp://php.net/manual/en/function.mysql-query.phphttp://docs.php.net/book.mysqli

}else{$result=$stmt->get_result();//asofphp5.4mysqli_resultimplementsTraversable,soyoucanuseitwithforeachforeach($resultas$row){...

Theseexamplesonlyillustratewhatshouldbedone(errorhandling),nothowtodoit.Productioncodeshouldntuseordie whenoutputtingHTML,elseitwill(attheveryleast)generateinvalidHTML.Also,databaseerrormessagesshouldntbedisplayedtonon-adminusers,asitdisclosestoomuchinformation .

Answer byjohn-conde

Thiserrormessageisdisplayedwhenyouhaveanerrorinyourquerywhichcausedittofail.Itwillmanifestitselfwhenusing:

mysql_fetch_array/mysqli_fetch_array()mysql_fetch_assoc()/mysqli_fetch_assoc()mysql_num_rows()/mysqli_num_rows()

Note:Thiserrordoesnotappearifnorowsareaffectedbyyourquery.Onlyaquerywithaninvalidsyntaxwillgeneratethiserror.

TroubleshootingSteps

Makesureyouhaveyourdevelopmentserverconfiguredtodisplayallerrors.Youcandothisbyplacingthisatthetopofyourfilesorinyourconfigfile:error_reporting(-1); .Ifyouhaveanysyntaxerrorsthiswillpointthemouttoyou.

Usemysql_error() .mysql_error()willreportanyerrorsMySQLencounteredwhileperformingyourquery.

Sampleusage:mysql_connect($host,$username,$password)ordie("cannotconnect");mysql_select_db($db_name)ordie("cannotselectDB");

$sql="SELECT*FROMtable_name";$result=mysql_query($sql);

if(false===$result){echomysql_error();}

RunyourqueryfromtheMySQLcommandlineoratoollikephpMyAdmin .Ifyouhaveasyntaxerrorinyourquerythiswilltellyouwhatitis.

Makesureyourquotesarecorrect.Amissingquotearoundthequeryoravaluecancauseaquerytofail.

Makesureyouareescapingyourvalues.Quotesinyourquerycancauseaquerytofail(andalsoleaveyouopentoSQLinjections).Usemysql_real_escape_string() toescapeyourinput.

Makesureyouarenotmixingmysqli_*andmysql_*functions.Theyarenotthe

http://www.phpfreaks.com/blog/or-die-must-diehttp://msdn.microsoft.com/en-us/library/ms995351.aspx#securityerrormessages_topic2http://stackoverflow.com/q/11674313http://stackoverflow.com/u/250259http://php.net/manual/en/function.error-reporting.phphttp://us3.php.net/manual/en/function.mysql-error.phphttp://www.phpmyadmin.net/home_page/index.phphttp://php.net/manual/en/function.mysql-real-escape-string.php

samethingandcannotbeusedtogether.(Ifyouregoingtochooseoneortheotherstickwithmysqli_*.Seebelowforwhy.)

Othertips

mysql_*functionsshouldnotbeusedfornewcode.Theyarenolongermaintainedandthecommunityhasbegunthedeprecationprocess .Insteadyoushouldlearnaboutpreparedstatements anduseeitherPDO orMySQLi .Ifyoucantdecide,thisarticle willhelptochoose.Ifyoucaretolearn,hereisgoodPDOtutorial .

Answer bynik

Erroroccurredherewasduetotheuseofsinglequotes(').Youcanputyourquerylikethis:mysql_query("SELECT*FROMUsersWHEREUserNameLIKE'".mysql_real_escape_string($username)."'");

Itsusingmysql_real_escape_stringforpreventionofSQLinjection.ThoughweshoulduseMySQLiorPDO_MYSQLextensionforupgradedversionofPHP(PHP5.5.0andlater),butforolderversionsmysql_real_escape_stringwilldothetrick.


Q:HowtoexportamysqldatabaseusingCommandPrompt?


IhaveadatabasethatisquitelargesoIwanttoexportitusingCommandPromptbutIdontknowhowto.

IamusingWAMP.


User:starx

Answer bystarx

Firstcheckifyourcommandlinerecognizesmysqlcommand.Ifnotgotocommand&typein:setpath=c:\wamp\bin\mysql\mysql5.1.36\bin

Thenusethiscommandtoexportyourdatabase:mysqldump-uYourUser-pYourDatabaseName>wantedsqlfile.sql

Youwillthenbepromptedforthedatabasepassword.

Thisexportsthedatabasetothepathyouarecurrentlyin,whileexecutingthiscommand

Note:Herearesomedetailedinstructions regardingbothimportandexport

http://news.php.net/php.internals/53799http://en.wikipedia.org/wiki/Prepared_statementhttp://us2.php.net/pdohttp://php.net/mysqlihttp://php.net/manual/en/mysqlinfo.api.choosing.phphttp://wiki.hashphp.org/PDO_Tutorial_for_MySQL_Developershttp://stackoverflow.com/q/2973247http://stackoverflow.com/u/290583http://stackoverflow.com/q/3031412http://stackoverflow.com/u/295264http://stackoverflow.com/q/3031414http://stackoverflow.com/u/295264http://www.thegeekstuff.com/2008/09/backup-and-restore-mysql-database-using-mysqldump/#more-184

Answer bysrinivasan.s

Simplyusethefollowingcommand,

ForExport:mysqldump-u[user]-p[db_name]|gzip>[filename_to_compress.sql.gz]

ForImport:gunzipcreatetablenumbers(adecimal(10,2),bfloat);mysql>insertintonumbersvalues(100,100);mysql>select@a:=(a/3),@b:=(b/3),@a*3,@b*3fromnumbers\G***************************1.row***************************@a:=(a/3):33.333333333@b:=(b/3):33.333333333333@a+@a+@a:99.999999999000000000000000000000@b+@b+@b:100

Thedecimaldidexactlywhatssupposedtodoonthiscases,ittruncatedtherest,thuslosingthe1/3part.

Soforsumsthedecimalisbetter,butfordivisionsthefloatisbetter,uptosomepoint,ofcourse.Imean,usingDECIMALwillnotgiveyouafailproofarithmeticinanymeans.

Hopethishelps.

Answer bymichael-petrotta

Afloatinmostenvironmentsisabinaryfloating-pointtype.Itcanaccuratelystorebase-2values(toacertainpoint),butcannotaccuratelystoremanybase-10(decimal)values.Floatsaremostappropriateforscientificcalculations.Theyrenotappropriateformostbusiness-orientedmath,andinappropriateuseoffloatswillbiteyou.Manydecimalvaluescantbeexactlyrepresentedinbase-2.0.1cant,forinstance,andsoyouseestrangeresultslike1.0-0.1=0.8999999.

Decimalsstorebase-10numbers.Decimalisangoodtypeformostbusinessmath(butanybuilt-inmoneytypeismoreappropriateforfinancialcalculations),wheretherangeofvaluesexceedsthatprovidedbyintegertypes,andfractionalvaluesareneeded.Decimals,asthenameimplies,aredesignedforbase-10numbers-theycanaccuratelystoredecimalvalues(again,toacertainpoint).

http://stackoverflow.com/q/5150274http://stackoverflow.com/u/278470http://stackoverflow.com/q/5150314http://stackoverflow.com/u/518445http://lists.mysql.com/mysql/201710http://stackoverflow.com/q/5150345http://stackoverflow.com/u/23897


Q:MySQLInsertintomultipletables?(Databasenormalization?)


Itriedsearchingawaytoinsertinformationinmultipletablesinthesamequery,butfoundoutitsimpossible?SoIwanttoinsertitbysimplyusingmutliplequeriesi.e;INSERTINTOusers(username,password)VALUES('test','test')INSERTINTOprofiles(userid,bio,homepage)VALUES('[idoftheuserhere?]','Helloworld!','http://www.stackoverflow.com')

ButhowcanIgivetheauto-incrementidfromtheusertothemanualuseridfortheprofiletable?


User:jay-wit

Answer bykonerak

No,youcantinsertintomultipletablesinoneMySQLcommand.Youcanhoweverusetransactions.BEGIN;INSERTINTOusers(username,password)VALUES('test','test');INSERTINTOprofiles(userid,bio,homepage)VALUES(LAST_INSERT_ID(),'Helloworld!','http://www.stackoverflow.com');COMMIT;

HavealookatLAST_INSERT_ID() toreuseautoincrementvalues.

Edit:yousaidAfterallthistimetryingtofigureitout,itstilldoesntwork.CantIsimplyputthejustgeneratedIDina$varandputthat$varinalltheMySQLcommands?

Letmeelaborate:thereare3possiblewayshere:

1. Isthecodeyouseeabove.ThisdoesitallinMySQL,andtheLAST_INSERT_ID()inthesecondstatementwillautomaticallybethevalueoftheautoincrement-columnthatwasinsertedinthefirststatement.

Unfortunately,whenthesecondstatementitselfinsertsrowsinatablewithanauto-incrementcolumn,theLAST_INSERT_ID()willbeupdatedtothatoftable2,andnottable1.Ifyoustillneedthatoftable1afterwards,wewillhavetostoreitinavariable.Thisleadsustoways2and3:

2. WillstocktheLAST_INSERT_ID()inaMySQLvariable:INSERTSELECTLAST_INSERT_ID()INTO@mysql_variable_here;INSERTINTOtable2(@mysql_variable_here,...);INSERTINTOtable3(@mysql_variable_here,...);

3. WillstocktheLAST_INSERT_ID()inaphpvariable(oranylanguagethatcanconnecttoadatabase,ofyourchoice):

http://stackoverflow.com/q/5178697http://stackoverflow.com/u/630020http://stackoverflow.com/q/5178713http://stackoverflow.com/u/327563http://dev.mysql.com/doc/refman/5.0/en/getting-unique-id.html

INSERTUseyourlanguagetoretrievetheLAST_INSERT_ID(),eitherbyexecutingthatliteralstatementinMySQL,orusingforexamplephpsmysql_insert_id()whichdoesthatforyouINSERT[useyourphpvariablehere]

WARNING

Whateverwayofsolvingthisyouchoose,youmustdecidewhatshouldhappenshouldtheexecutionbeinterruptedbetweenqueries(forexample,yourdatabase-servercrashes).Ifyoucanlivewithsomehavefinished,othersnot,dontreadon.

Ifhoweveryoudecideeitherallqueriesfinish,ornonefinish-Idonotwantrowsinsometablesbutnomatchingrowsinothers,Ialwayswantmydatabasetablestobeconsistent,youneedtowrapallstatementsinatransaction.ThatswhyIusedtheBEGINandCOMMIThere.

Commentagainifyouneedmoreinfo:)


Q:CantconnecttolocalMySQLserverthroughsocket/var/mysql/mysql.sock(38)


Iamhavingabigproblemtryingtoconnecttomysql.WhenIrun:/usr/local/mysql/bin/mysqlstart

Ihavethefollowingerror:Can'tconnecttolocalMySQLserverthroughsocket'/var/mysql/mysql.sock'(38)

Idohavemysql.sockunderthe/var/mysqldirectory.

In/etc/my.cnfIhave:[client]port=3306socket=/var/mysql/mysql.sock

[mysqld]port=3306socket=/var/mysql/mysql.sockkey_buffer_size=16Mmax_allowed_packet=8M

andin/etc/php.iniIhave:;DefaultsocketnameforlocalMySQLconnects.Ifempty,usesthebuilt-in;MySQLdefaults.mysql.default_socket=/var/mysql/mysql.sock

Ihaverestartedapacheusingsudo/opt/local/apache2/bin/apachectlrestart

http://stackoverflow.com/q/5376427

ButIstillhavetheerror.

Otherwise,IdontknowifthatsrelevantbutwhenIdomysql_config--socketsIget--socket[/tmp/mysql.sock]


User:lambivist

Answer bymarimaf

Ifyourfilemy.cnf(usuallyinthe/etc/mysql/folder)iscorrectlyconfiguredwithsocket=/var/lib/mysql/mysql.sock

youcancheckifmysqlisrunningwiththefollowingcommand:mysqladmin-uroot-pstatus

trychangingyourpermissiontomysqlfolder.Ifyouareworkinglocally,youcantry:sudochmod-R755/var/lib/mysql/

thatsolveditforme

Answer bywaqas

areyousureyouinstalledmysqlaswellasmysqlserver..

ForexampletoinstallmySqlserverIlluseyumorapttoinstallbothmysqlcommandlinetoolandtheserver:yum-yinstallmysqlmysql-server(orapt-getinstallmysqlmysql-server)

EnabletheMySQLservice:/sbin/chkconfigmysqldon

StarttheMySQLserver:/sbin/servicemysqldstart

afterwardssettheMySQLrootpassword:mysqladmin-urootpassword'new-password'(withthequotes)

Ihopeithelps.

Answer bymaurizio

Aquickworkaroundthatworkedforme:tryusingthelocalipaddress(127.0.0.1)insteadoflocalhostinmysql_connect().ThisforcesphptoconnectthroughTCP/IPinsteadofaunixsocket.


http://stackoverflow.com/u/615503http://stackoverflow.com/q/8084959http://stackoverflow.com/u/592795http://stackoverflow.com/q/11178032http://stackoverflow.com/u/819344http://stackoverflow.com/q/8339695http://stackoverflow.com/u/422803

Q:MySQLOPTIMIZEalltables?


MySQLhasanOPTIMIZETABLE commandwhichcanbeusedtoreclaimunusedspaceinaMySQLinstall.Isthereaway(built-incommandorcommonstoredprocedure)torunthisoptimizationforeverytableinthedatabaseand/orserverinstall,oristhissomethingyoudhavetoscriptupyourself?


User:alan-storm

Answer byike-walker

Youcanusemysqlcheck todothisatthecommandline.

Onedatabase:mysqlcheck-o

Alldatabases:mysqlcheck-o--all-databases


Q:GetallcolumnsfromallMySQLtables


IsthereafastwayofgettingallcolumnnamesfromalltablesinMySQL,withouthavingtolistallthetables?


User:dieter

Answer bynick-rulezselect*frominformation_schema.columnswheretable_schema='your_db'orderbytable_name,ordinal_position


Q:MySQLstringreplace


Ihaveacolumncontainingurls(id,url):

http://stackoverflow.com/q/5474662http://dev.mysql.com/doc/refman/5.1/en/optimize-table.htmlhttp://stackoverflow.com/u/4668http://stackoverflow.com/q/5475582http://stackoverflow.com/u/233196http://dev.mysql.com/doc/refman/5.0/en/mysqlcheck.htmlhttp://stackoverflow.com/q/5648420http://stackoverflow.com/u/704164http://stackoverflow.com/q/5648713http://stackoverflow.com/u/344491http://stackoverflow.com/q/5956993

http://www.example.com/articles/updates/43http://www.example.com/articles/updates/866http://www.example.com/articles/updates/323http://www.example.com/articles/updates/seo-urlhttp://www.example.com/articles/updates/4?something=test

Idliketochangethewordupdatestonews.Isitpossibletodothiswithascript?


User:n00b

Answer bygiraldiUPDATEyour_tableSETyour_field=REPLACE(your_field,'articles/updates/','articles/news/')WHEREyour_fieldLIKE'%articles/updates/%'

http://to.ly/iLjP

Answer byonteria_

Yes,MySQLhasaREPLACE()function:mysql>SELECTREPLACE('www.mysql.com','w','Ww');->'WwWwWw.mysql.com'

http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_replace

NotethatitseasierifyoumakethatanaliaswhenusingSELECTSELECTREPLACE(string_column,'search','replace')asurl.


Q:mySQLselectonecolumnDISTINCT,withcorrespondingothercolumns

Tags:mysql(PrevQ)(NextQ)IDFirstNameLastName1JohnDoe2BugsBunny3JohnJohnson

IwanttoselectDISTINCTresultsfromtheFirstNamecolumn,butIneedthecorrespondingIDandLastName.

TheresultsetneedstoshowonlyoneJohn,butwithanIDof1andaLastNameofDoe.


User:m-r

Answer bydiecho

trythisquerySELECTID,FirstName,LastNameFROMtableGROUPBY(FirstName)

http://stackoverflow.com/u/276315http://stackoverflow.com/q/14586441http://stackoverflow.com/u/851045http://to.ly/iLjPhttp://stackoverflow.com/q/5957021http://stackoverflow.com/u/742496http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_replacehttp://stackoverflow.com/q/5967130http://stackoverflow.com/u/638531http://stackoverflow.com/q/5967209http://stackoverflow.com/u/155861


Q:MySqlexportschemawithoutdata


ImusingaMySqldatabasewithaJavaprogram,nowIwanttogivetheprogramtosomebodyelse.

HowtoexporttheMySqldatabasestructurewithoutthedatainit,justthestructure?


User:darth-blue-ray

Answer bydaric

Youcandowiththeno-dataoptionwithmysqldumpcommandmysqldump-uroot-p--no-datadbname>schema.sql

Answer byonteria_

Yes,youcanusemysqldumpwiththe--no-dataoption:mysqldump-uuser-hlocalhost--no-data-pdatabase>database.sql


Q:HowcanyoudeterminehowmuchdiskspaceaparticularMySQLtableistakingup?


IsthereaquickwaytodeterminehowmuchdiskspaceaparticularMySQLtableistakingup?ThetablemaybeMyISAMorInnodb.


User:dan

Answer byrolandomysqldba

Foratablemydb.mytablerunthisfor:

BYTES

SELECT(data_length+index_length)tablesizeFROMinformation_schema.tablesWHEREtable_schema='mydb'andtable_name='mytable';

http://stackoverflow.com/q/6175473http://stackoverflow.com/u/753983http://stackoverflow.com/q/6175506http://stackoverflow.com/u/611232http://stackoverflow.com/q/6175500http://stackoverflow.com/u/742496http://stackoverflow.com/q/6474591http://stackoverflow.com/u/232417http://stackoverflow.com/q/6474642http://stackoverflow.com/u/491757

KILOBYTES

SELECT(data_length+index_length)/power(1024,1)tablesize_kbFROMinformation_schema.tablesWHEREtable_schema='mydb'andtable_name='mytable';

MEGABYTES

SELECT(data_length+index_length)/power(1024,2)tablesize_mbFROMinformation_schema.tablesWHEREtable_schema='mydb'andtable_name='mytable';

GIGABYTES

SELECT(data_length+index_length)/power(1024,3)tablesize_gbFROMinformation_schema.tablesWHEREtable_schema='mydb'andtable_name='mytable';

GENERIC

HereisagenericquerywherethemaximumunitdisplayisTB(TeraBytes)SkipcodeblockSELECTCONCAT(FORMAT(DAT/POWER(1024,pw1),2),'',SUBSTR(units,pw1*2+1,2))DATSIZE,CONCAT(FORMAT(NDX/POWER(1024,pw2),2),'',SUBSTR(units,pw2*2+1,2))NDXSIZE,CONCAT(FORMAT(TBL/POWER(1024,pw3),2),'',SUBSTR(units,pw3*2+1,2))TBLSIZEFROM(SELECTDAT,NDX,TBL,IF(px>4,4,px)pw1,IF(py>4,4,py)pw2,IF(pz>4,4,pz)pw3FROM(SELECTdata_lengthDAT,index_lengthNDX,data_length+index_lengthTBL,FLOOR(LOG(IF(data_length=0,1,data_length))/LOG(1024))px,FLOOR(LOG(IF(index_length=0,1,index_length))/LOG(1024))py,FLOOR(LOG(IF(data_length+index_length=0,1,data_length+index_length))/LOG(1024))pzFROMinformation_schema.tablesWHEREtable_schema='mydb'ANDtable_name='mytable')AA)A,(SELECT'BKBMBGBTB'units)B;

GiveitaTry!!!


Q:MYSQLUpdateStatementInnerJoinTables


Ihavenoideawhattheproblemis.UsingMySQL5.0igetacompileerrorwhenattemptingtorunthefollowingMYSQLupdatestatementUPDATEbSETb.mapx=g.latitude,b.mapy=g.longitudeFROMbusinessASbINNERJOINbusiness_geocodegONb.business_id=g.business_idWHERE(b.mapx=''orb.mapx=0)and


g.latitude>0

allthefieldnamesarecorrect.Anythoughts?


User:vibration-of-life

Answer byasaph

Trythis:UPDATEbusinessASbINNERJOINbusiness_geocodeASgONb.business_id=g.business_idSETb.mapx=g.latitude,b.mapy=g.longitudeWHERE(b.mapx=''orb.mapx=0)andg.latitude>0

Update:

Sinceyousaidthequeryyieldedasyntaxerror,IcreatedsometablesthatIcouldtestitagainstandconfirmedthatthereisnosyntaxerrorinmyquery:Skipcodeblockmysql>createtablebusiness(business_idintunsignedprimarykeyauto_increment,mapxvarchar(255),mapyvarchar(255))engine=innodb;QueryOK,0rowsaffected(0.01sec)

mysql>createtablebusiness_geocode(business_geocode_idintunsignedprimarykeyauto_increment,business_idintunsignednotnull,latitudevarchar(255)notnull,longitudevarchar(255)notnull,foreignkey(business_id)referencesbusiness(business_id))engine=innodb;QueryOK,0rowsaffected(0.01sec)

mysql>UPDATEbusinessASb->INNERJOINbusiness_geocodeASgONb.business_id=g.business_id->SETb.mapx=g.latitude,->b.mapy=g.longitude->WHERE(b.mapx=''orb.mapx=0)and->g.latitude>0;QueryOK,0rowsaffected(0.00sec)Rowsmatched:0Changed:0Warnings:0

See?Nosyntaxerror.ItestedagainstMySQL5.5.8.


Q:Howtochangemax_allowed_packetsize


IamhavingaproblemwithBLOBfieldsinmyMySQLdatabase-whenuploadingfileslargerthanapprox1MBIgetanerrorPacketslargerthanmax_allowed_packetarenotallowed.

Hereiswhativetried:

InMySQLQueryBrowserIranashowvariableslike'max_allowed_packet'whichgaveme1048576.

ThenIexecutethequerysetglobalmax_allowed_packet=33554432followedbyshowvariableslike'max_allowed_packet'-itgivesme33554432asexpected.

http://stackoverflow.com/u/719316http://stackoverflow.com/q/8057585http://stackoverflow.com/u/166339http://stackoverflow.com/q/8062496

ButwhenIrestarttheMySQLserveritmagicallygoesbackto1048576.WhatamIdoingwronghere?

Bonusquestion,isitpossibletocompressaBLOBfield?


User:muleskinner

Answer bymanuel

Changeinthemy.inior~/.my.cnffilebyincludingthesinglelineunder[mysqld]sectioninyourfile:max_allowed_packet=500M

thenrestarttheMySQLserviceandyouaredone.

Seethedocumentation forfurtherinformation.

Answer bytehshrike

Themax_allowed_packet variablecanbesetgloballybyrunningaquery.

However,ifyoudonotchangeitinthemy.inifile(asdragon112suggested),thevaluewillresetwhentheserverrestarts,evenifyousetitglobally.

Tochangethesettingforeveryoneuntiltheserverrestarts:SETGLOBALmax_allowed_packet=1073741824;


Q:MySQL:determinewhichdatabaseisselected?


Aftercallingmysql_select_dbtograbadatabase,isthereanywaytolateroutputthenameofthedatabasethatiscurrentlyselected?ThisseemsverybasicbutIcouldntfindanythingonphp.netorstackoverflow(allresultsarefornodatabaseselected).


User:andrewtweber

Answer bycwallenpoole

Justusemysql_query(ormysqli_query,evenbetter,orusePDO,bestofall)with:SELECTDATABASE()FROMDUAL;

Addendum:

http://stackoverflow.com/u/246277http://stackoverflow.com/q/8062538http://stackoverflow.com/u/703595https://dev.mysql.com/doc/refman/5.5/en/packet-too-large.htmlhttp://stackoverflow.com/q/8062996http://stackoverflow.com/u/201789http://dev.mysql.com/doc/refman/5.5/en/server-system-variables.html#sysvar_max_allowed_packethttp://stackoverflow.com/q/8096550http://stackoverflow.com/u/704803http://stackoverflow.com/q/8096574http://stackoverflow.com/u/57191

ThereismuchdiscussionoverwhetherornotFROMDUALshouldbeincludedinthisornot.Onatechnicallevel,itisaholdoverfromOracleandcansafelyberemoved.Ifyouareinclined,youcanusethefollowinginstead:SELECTDATABASE();

Thatsaid,itisperhapsimportanttonote,thatwhileFROMDUALdoesnotactuallydoanything,itisvalidMySQLsyntax.Fromastrictperspective,includingbracesinasinglelineconditionalinJavaScriptalsodoesnotdoanything,butitisstillavalidpractice.


Q:EnableremoteMySQLconnection:ERROR1045(28000):Accessdeniedforuser


MySQL5.1.31runningonWindowsXP.

FromthelocalMySQLserver(192.168.233.142)Icanconnectasrootasfollows:>mysql--host=192.168.233.142--user=root--password=redacted

Fromaremotemachine(192.168.233.163),Icanseethatthemysqlportisopen:#telnet192.168.233.1423306Trying192.168.233.142Connectedto192.168.233.142(192.168.233.142).

Butwhentryingtoconnecttomysqlfromtheremotemachine,Ireceive:#mysql--host=192.168.233.142--user=root--password=redactedERROR1045(28000):Accessdeniedforuser'root'@'192.168.233.163'(usingpassword:YES)

Ihaveonly2entriesinmysql.user:HostUserPassword--------------------------------------localhostroot*blahblahblah%root[sameasabove]

WhatmoredoIneedtodotoenableremoteaccess?

EDIT

AssuggestedbyPaulobelow,Itriedreplacingthemysql.userentryfor%withanIPspecificentry,somyusertablenowlookslikethis:HostUserPassword------------------------------------------localhostroot*blahblahblah192.168.233.163root[sameasabove]

Ithenrestartedthemachine,buttheproblempersists.


User:mike-chamberlain

http://stackoverflow.com/q/8380797http://stackoverflow.com/u/289319

Answer byoctavio

Youhavetoputthisasroot:GRANTALLPRIVILEGESON*.*TO'USERNAME'@'IP'IDENTIFIEDBY'PASSWORD'withgrantoption;

;

whereIPistheIPyouwanttoallowaccessandUSERNAMEistheuseryouusetoconnect

IfyouwanttoallowaccessfromanyIPjustput%insteadofyourIP

andthenyouonlyhavetoputFLUSHPRIVILEGES;

Orrestartmysqlserverandthatsit.

Answer bydrumchaps

IwasgettingthesameerroraftergrantingremoteaccessuntilImadethis:

From/etc/mysql/my.cnf#Insteadofskip-networkingthedefaultisnowtolistenonlyon#localhostwhichismorecompatibleandisnotlesssecure.#bind-address=127.0.0.1

(commentthisline:bind-address=127.0.0.1)

Thenrunservicemysqlrestart.

Answer byravi-kant

BydefaultinMySQLserverremoteaccessisdisabled.Theprocesstoprovidearemoteaccesstouseris.

1. GotomysqlbinfolderoraddittoPATH2. Logintorootbymysql-uroot-proot(orwhatevertherootpasswordis.)3. Onsuccessyouwillgetmysql>4. Providegrantaccessallforthatuser.

GRANTALLPRIVILEGESON*.*TO'username'@'IP'IDENTIFIEDBY'password';

HereIPisIPaddressforwhichyouwanttoallowremoteaccess,ifweput%anyIPaddresscanaccessremotely.

Example:C:\Users\UserName>cdC:\ProgramFiles(x86)\MySQL\MySQLServer5.0\bin

C:\ProgramFiles(x86)\MySQL\MySQLServer5.0\bin>mysql-uroot-proot

mysql>GRANTALLPRIVILEGESON*.*TO'root'@'%'IDENTIFIEDBY'root';QueryOK,0rowsaffected(0.27sec)

mysql>FLUSHPRIVILEGES;QueryOK,0rowsaffected(0.25sec)

http://stackoverflow.com/q/12844804http://stackoverflow.com/u/1738901http://stackoverflow.com/q/21151255http://stackoverflow.com/u/3200527http://stackoverflow.com/q/19359062http://stackoverflow.com/u/2151298

Thisforaotheruser.mysql>GRANTALLPRIVILEGESON*.*TO'testUser'@'%'IDENTIFIEDBY'testUser';QueryOK,0rowsaffected(0.00sec)

mysql>FLUSHPRIVILEGES;QueryOK,0rowsaffected(0.00sec)

Hopethiswillhelp


Q:HowdoIcheckifacolumnisemptyornullinmysql


Ihaveacolumninatablewhichmightcontainnulloremptyvalues.HowdoIcheckifacolumnisemptyornullintherowspresentinatable.(e.g.nullor''or''or''and)


User:priya

Answer bymaek

Thiswillselectallrowswheresome_colisNULLor''(emptystring)SELECT*FROMtableWHEREsome_colISNULLORsome_col='';

Answer byonedaywhen

AsdefinedbytheSQL-92Standard,whencomparingtwostringsofdifferingwidths,thenarrowervalueisright-paddedwithspacestomakeitissamewidthasthewidervalue.Therefore,allvaluesthatconsistexclusivelyinvolvingzeroormorespaceswillbedeemedtobeequale.g.''=''ISTRUE''=''ISTRUE''=''ISTRUE''=''ISTRUEetc

Therefore,thisshouldworkregardlessofhowmanyspacesmakeupthesome_colvalue:SELECT*FROMTWHEREsome_colISNULLORsome_col='';

ormoresuccinctly:SELECT*FROMTWHERENULLIF(some_col,'')ISNULL;


http://stackoverflow.com/q/8470813http://stackoverflow.com/u/1004443http://stackoverflow.com/q/8470865http://stackoverflow.com/u/184600http://stackoverflow.com/q/8474327http://stackoverflow.com/u/15354

Q:DoesMySQLforeign_key_checksaffecttheentiredatabase?


WhenIexecutethiscommandinmysql:SETFOREIGN_KEY_CHECKS=0;

Doesitaffectthewholeengineoritisonlymycurrenttransaction?


User:sean-nguyen

Answer byalmo

Itissession-based.Doatesttobesure,butthatsmyunderstandingofit.

Answer byron-inbar

Actually,therearetwoforeign_key_checksvariables:aglobalvariableandalocal(persession)variable.Uponconnection,thesessionvariableisinitializedtothevalueoftheglobalvariable.ThecommandSETforeign_key_checksmodifiesthesessionvariable.Tomodifytheglobalvariable,useSETGLOBALforeign_key_checksorSET@@global.foreign_key_checks.

Consultthefollowingmanualsections:http://dev.mysql.com/doc/refman/5.7/en/using-system-variables.htmlhttp://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html


Q:MySQL:Selectonlyuniquevaluesfromacolumn


IhaveaMySQLtablewhichcontainsthefollowingtypeofinformation:Dateproduct2011-12-12azd2011-12-12yxm2011-12-10sdx2011-12-10ssdd

HereisanexampleofascriptIusetogetdatafromthistable:Skipcodeblock

$sql=mysql_query("SELECT*FROMbuyORDERBYDate");while($row=mysql_fetch_array($sql)){

echo"buy".date("j,MY",strtotime($row["Date"]))."";

}mysql_close($con);?>

Thisscriptdisplayseverydatefromthetable,e.g.12.dec201112.dec.201110.dec.201110.dec.2011

Iwouldliketoonlydisplayuniquedates,e.g.12.dec.201110.dec.2011


User:meandme

Answer bylon-rodenburg

UsetheDISTINCT operatorinMySQL:SELECTDISTINCT(Date)ASDateFROMbuyORDERBYDateDESC;


Q:ERROR1044(42000):Accessdeniedforuser@localhosttodatabasedb


IwanttobeginwritingqueriesinMySQL.

showgrantsshows:+--------------------------------------+|Grantsfor@localhost|+--------------------------------------+|GRANTUSAGEON*.*TO''@'localhost'|+--------------------------------------+

Idonothaveanyuser-idbutwhenIwanttomakeauserIdonthaveprivilleges,alsoIdontknowhowtomakeprivilegeswhenevenIdonthaveoneuser!mysql>CREATEUSER'parsa'@'localhost'IDENTIFIEDBY'parsa';ERROR1227(42000):Accessdenied;youneed(atleastoneof)theCREATEUSERprivilege(s)forthisoperation

Itriedtosigninasroot:mysql>mysql-uroot-p;ERROR1064(42000):YouhaveanerrorinyourSQLsyntax;checkthemanualthatcorrespondstoyourMySQLserverversionfortherightsyntaxtousenear'mysql-uroot-p'atline1mysql>mysql-uroot-proot;

http://stackoverflow.com/u/849530http://stackoverflow.com/q/8571928http://stackoverflow.com/u/1101134https://dev.mysql.com/doc/refman/5.0/en/distinct-optimization.htmlhttp://stackoverflow.com/q/8838777

ERROR1064(42000):YouhaveanerrorinyourSQLsyntax;checkthemanualthatcorrespondstoyourMySQLserverversionfortherightsyntaxtousenear'mysql-uroot-proot'atline1


User:nickool

Answer bynowhy

No,youshouldrunmysql-uroot-pinbash,notattheMySQLcommand-line.Ifyouareinmysql,youcanexitbytypingexit.


Q:Howtogetthesizesofthetablesofamysqldatabase?


Icanrunthisquerytogetthesizesofalltablesinamysqldatabase:showtablestatusfrommyDatabaseName;

Iwouldlikesomehelpinunderstandingtheresults.Iamlookingfortableswiththelargestsizes.

WhichcolumnshouldIlookat?


User:jpashs

Answer bychapmic

Youcanusethisquerytoshowthesizeofatable(althoughyouneedtosubstitutethevariablesfirst):SELECTtable_nameAS`Table`,round(((data_length+index_length)/1024/1024),2)`SizeinMB`FROMinformation_schema.TABLESWHEREtable_schema="$DB_NAME"ANDtable_name="$TABLE_NAME";

orthisquerytolistthesizeofeverytableineverydatabase,largestfirst:SELECTtable_schemaas`Database`,table_nameAS`Table`,round(((data_length+index_length)/1024/1024),2)`SizeinMB`FROMinformation_schema.TABLESORDERBY(data_length+index_length)DESC;

Answer bysumith-harshanSELECTTABLE_NAMEAS"TableName",table_rowsAS"QuantofRows",ROUND((data_length+index_length)/1024,2)AS"TotalSizeKb"FROMinformation_schema.TABLES

http://stackoverflow.com/u/974380http://stackoverflow.com/q/8839017http://stackoverflow.com/u/1136992http://stackoverflow.com/q/9620198http://stackoverflow.com/u/1121218http://stackoverflow.com/q/9620273http://stackoverflow.com/u/1242826http://stackoverflow.com/q/12439645http://stackoverflow.com/u/885226

WHEREinformation_schema.TABLES.table_schema='YOURSCHEMANAME/DATABASENAMEHERE'LIMIT0,30

Youcangetschemanamefrominformation_schema->SCHEMATAtable->SCHEMA_NAMEcolumn

AdditionalYoucangetsizeofthemysqldatabasesasfollowing.SELECTtable_schema"DBName",Round(Sum(data_length+index_length)/1024/1024,1)"DBSizeinMB"FROMinformation_schema.tablesGROUPBYtable_schema;

ResultDBName|DBSizeinMB

mydatabase_wrdp39.1information_schema0.0

Youcangetadditionaldetailsinhere.


Q:WhatdoesitmeanwhenMySQLisinthestateSendingdata?


WhatdoesitmeaniftheMysqlquery:SHOWPROCESSLIST;

returnsSendingdataintheStatecolumn?

IimagineitmeansthequeryhasbeenexecutedandMySQLissendingresultDatatotheclientbutImwonderingwhyitstakingsomuchtime(uptoanhour).

Thankyou.


User:user1345414

Answer byquassnoi

Thisisquiteamisleadingstatus.Itshouldbecalledreadingandfilteringdata.

ThismeansthatMySQLhassomedatastoredonthedisk(orinmemory)whichisyettobereadandsentover.Itmaybethetableitself,anindex,atemporarytable,asortedoutputetc.

Ifyouhavea1Mrecordstable(withoutanindex)ofwhichyouneedonlyonerecord,MySQLwillstilloutputthestatusassendingdatawhilescanningthetable,despitethefactithasnotsentanythingyet.


http://webexplorar.com/how-can-i-get-database-table-sizes/http://stackoverflow.com/q/10347193http://stackoverflow.com/u/1345414http://stackoverflow.com/q/10347999http://stackoverflow.com/u/55159

Q:ERROR2006(HY000):MySQLserverhasgoneaway


IgetthiserrorwhenItrytosourcealargeSQLfile(abigINSERTquery).Skipcodeblockmysql>sourcefile.sqlERROR2006(HY000):MySQLserverhasgoneawayNoconnection.TryingtoreconnectConnectionid:2Currentdatabase:***NONE***

ERROR2006(HY000):MySQLserverhasgoneawayNoconnection.TryingtoreconnectConnectionid:3Currentdatabase:***NONE***

Nothinginthetableisupdated.Ivetrieddeletingandundeletingthetable/database,aswellasrestartingMySQL.Noneofthesethingsresolvetheproblem.

Hereismymax-packetsize:+--------------------+---------+|Variable_name|Value|+--------------------+---------+|max_allowed_packet|1048576|+--------------------+---------+

Hereisthefilesize:$ls-sfile.sql79512file.sql

WhenItrytheothermethod$./mysql-uroot-pmy_db>>------------------------------------------------------------------------------------------------------^^^^Ûnquotedfunction//----------------------------------------------------------------------------------------------------^^^^^^^^^^^^Single-quotedDATE//-----------------------------------------------------------------------------------^^^^^^^^^^^^^^^Single-quotedstrings//-----------------------------------------------------------------------------^^^^Ûnquotedkeyword//--------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Backticktable&column

Variableinterpolation

Thequotingpatternsforvariablesdonotchange,althoughifyouintendtointerpolatethevariablesdirectlyinastring,itmustbedouble-quotedinPHP.JustmakesurethatyouhaveproperlyescapedthevariablesforuseinSQL.(ItisrecommendedtouseanAPIsupportingpreparedstatementsinstead,asprotectionagainstSQLinjection).//Samethingwithsomevariablereplacements//Here,avariabletablename$tableisbacktick-quoted,andvariables//intheVALUESlistaresingle-quoted$query="INSERTINTO`$table`(ìd`,`col1`,`col2`,`date`)VALUES(NULL,'$val1','$val2','$date')";

Preparedstatements

http://stackoverflow.com/u/1101095http://stackoverflow.com/q/11321508http://stackoverflow.com/u/541091http://dev.mysql.com/doc/refman/5.5/en/reserved-words.html

Whenworkingwithpreparedstatements,consultthedocumentationtodeterminewhetherornotthestatementsplaceholdersmustbequoted.ThemostpopularAPIsavailableinPHP,PDOandMySQLi,expectunquotedplaceholders,asdomostpreparedstatementAPIsinotherlanguages://PDOexamplewithnamedparameters,unquoted$query="INSERTINTO`table`(`id`,`col1`,`col2`,`date`)VALUES(:id,:col1,:col2,:date)";

//MySQLiexamplewith?parameters,unquoted$query="INSERTINTO`table`(`id`,`col1`,`col2`,`date`)VALUES(?,?,?,?)";

Charactersrequringbacktickquotinginidentifiers:

AccordingtoMySQLdocumentation ,youdonotneedtoquote(backtick)identifiersusingthefollowingcharacterset:

ASCII:[0-9,a-z,A-Z$_](basicLatinletters,digits0-9,dollar,underscore)

Youcanusecharactersbeyondthatsetastableorcolumnidentifiers,includingwhitespaceforexample,butthenyoumustquote(backtick)them.

Answer bysalman-a

TherearetwotypesofquotesinMySQL:

1. 'forenclosingstringliterals2. `forenclosingidentifierssuchastableandcolumnnames

Andthenthereis"whichisaspecialcase.Itcouldbeusedforoneofabove-mentionedpurposesatatimedependingonMySQLserverssql_mode :

1. Bydefaultthe"charactercanbeusedtoenclosestringliteralsjustlike'2. InANSI_QUOTES modethe"charactercanbeusedtoencloseidentifiersjustlike`

Thefollowingquerywillproducedifferentresults(orerrors)dependingonSQLmode:

SELECT"column"FROMtableWHEREfoo="bar"

ANSI_QUOTESdisabled

Thequerywillselectthestringliteral"column"wherecolumnfooisequaltostring"bar"

ANSI_QUOTESenabled

Thequerywillselectthecolumncolumnwherecolumnfooisequaltocolumnbar

Whentousewhat

Isuggestthatyouavoidusing"sothatyourcodebecomesindependentofSQLmodes

http://dev.mysql.com/doc/refman/5.5/en/identifiers.htmlhttp://stackoverflow.com/q/14123649http://stackoverflow.com/u/87015http://dev.mysql.com/doc/refman/5.6/en/sql-mode.htmlhttp://dev.mysql.com/doc/refman/5.6/en/sql-mode.html#sqlmode_ansi_quotes

Alwaysquoteidentifierssinceitisagoodpractice(quiteafewquestionsonSOdiscussthis)


Q:CastfromVARCHARtoINT-MySQL


MyCurrentDataforSELECTPROD_CODEFROM`PRODUCT`

isPROD_CODE25782210911

Ihavetriedallthefourqueriesandnonework.(Ref )SELECTCAST(PROD_CODE)ASINTFROMPRODUCT;

SELECTCAST(PROD_CODEASINT)FROMPRODUCT;

SELECTCAST(PROD_CODE)ASINTEGERFROMPRODUCT;

SELECTCAST(PROD_CODEASINTEGER)FROMPRODUCT;

Allthrowsyntaxerrorssuchasbelow:

YouhaveanerrorinyourSQLsyntax;checkthemanualthatcorrespondstoyourMySQLserverversionfortherightsyntaxtousenear)ASINTFROMPRODUCTLIMIT0,30atline1

YouhaveanerrorinyourSQLsyntax;checkthemanualthatcorrespondstoyourMySQLserverversionfortherightsyntaxtousenearINTEGER)FROMPRODUCTLIMIT0,30atline1

WhatistherightsyntaxtocastvarchartointegerinMySQL?

MySQLVersion:5.5.16


User:emaillenin

Answer byeggyal

AsdescribedinCastFunctionsandOperators :

Thetypefortheresultcanbeoneofthefollowingvalues:

http://stackoverflow.com/q/12126991http://dev.mysql.com/doc/refman/5.5/en/cast-functions.html#function_casthttp://stackoverflow.com/u/184184http://stackoverflow.com/q/12127022http://stackoverflow.com/u/623041http://dev.mysql.com/doc/en/cast-functions.html#function_cast

BINARY[(N)]CHAR[(N)]DATEDATETIMEDECIMAL[(M[,D])]SIGNED[INTEGER]TIMEUNSIGNED[INTEGER]

Therefore,youshoulduse:SELECTCAST(PROD_CODEASUNSIGNED)FROMPRODUCT


Q:ERROR:Error1005:Cantcreatetable(errno:121)


ImhavingtroubleswithforwardengineeringmyMySQLdatabaseintoWAMPserver..Iwasgoingtopostanimageoftheschemabutasthisismyfirstposticant..

Belowistheexecutedscript..Skipcodeblockuseaquaticstar;

SET@OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS,UNIQUE_CHECKS=0;SET@OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS,FOREIGN_KEY_CHECKS=0;SET@OLD_SQL_MODE=@@SQL_MODE,SQL_MODE='TRADITIONAL,ALLOW_INVALID_DATES';

-----------------------------------------------------Table`Students`-----------------------------------------------------DROPTABLEIFEXISTS`Students`;

CREATETABLEIFNOTEXISTS`Students`(ìd`VARCHAR(10)NOTNULL,`studentName`VARCHAR(45)NOTNULL,`gender`CHARNOTNULL,`birthDate`DATETIMENOTNULL,`mNo`VARCHAR(10)NOTNULL,`contactName`VARCHAR(45)NOTNULL,`contactEmail`VARCHAR(45)NOTNULL,`contactPhoneÌNT(10)NOTNULL,`startDate`DATETIMENOTNULL,`remarks`VARCHAR(200)NULL,PRIMARYKEY(ìd`))ENGINE=InnoDB;

-----------------------------------------------------Table`WaitingList`-----------------------------------------------------DROPTABLEIFEXISTS`WaitingList`;

CREATETABLEIFNOTEXISTS`WaitingList`(`wait_id`VARCHAR(5)NOTNULL,`name`VARCHAR(45)NULL,`contactName`VARCHAR(45)NULL,`contactPhoneÌNT(10)NULL,`contactEmail`VARCHAR(45)NULL,`status`CHARNULL,`remarks`VARCHAR(200)NULL,PRIMARYKEY(`wait_id`))ENGINE=InnoDB;

-----------------------------------------------------Table`Schedule`-----------------------------------------------------


DROPTABLEIFEXISTS`Schedule`;

CREATETABLEIFNOTEXISTS`Schedule`(`lesson_id`VARCHAR(10)NOTNULL,`day`VARCHAR(3)NOTNULL,`branch`VARCHAR(30)NOTNULL,`level`VARCHAR(30)NOTNULL,`time`TIMENOTNULL,àe`VARCHAR(45)NOTNULL,PRIMARYKEY(`lesson_id`))ENGINE=InnoDB;

-----------------------------------------------------Table`Link`-----------------------------------------------------DROPTABLEIFEXISTS`Link`;

CREATETABLEIFNOTEXISTS`Link`(`link_id`VARCHAR(10)NOTNULL,ìd`VARCHAR(10)NOTNULL,`lesson_id`VARCHAR(10)NOTNULL,PRIMARYKEY(`link_id`),INDEXìd_idx`(ìdÀSC),INDEX`lesson_id_idx`(`lesson_idÀSC),CONSTRAINTìd`FOREIGNKEY(ìd`)REFERENCES`Students`(ìd`)ONDELETENOACTIONONUPDATENOACTION,CONSTRAINT`lesson_id`FOREIGNKEY(`lesson_id`)REFERENCES`Schedule`(`lesson_id`)ONDELETENOACTIONONUPDATENOACTION)ENGINE=InnoDB;

-----------------------------------------------------TableÀttendance`-----------------------------------------------------DROPTABLEIFEXISTSÀttendance`;

CREATETABLEIFNOTEXISTSÀttendance`(`date`DATETIMENOTNULL,àttendance`VARCHAR(5)NOTNULL,`link_id`VARCHAR(10)NOTNULL,INDEX`link_id_idx`(`link_idÀSC),CONSTRAINT`link_id`FOREIGNKEY(`link_id`)REFERENCES`Link`(`link_id`)ONDELETENOACTIONONUPDATENOACTION)ENGINE=InnoDB;

SETSQL_MODE=@OLD_SQL_MODE;SETFOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS;SETUNIQUE_CHECKS=@OLD_UNIQUE_CHECKS;-----------------------------------------------------Datafortable`Students`-----------------------------------------------------STARTTRANSACTION;INSERTINTO`Students`(ìd`,`studentName`,`gender`,`birthDate`,`mNo`,`contactName`,`contactEmail`,`contactPhone`,`startDate`,`remarks`)VALUES('s001','SamKhew','m','12/12/1991','nm','MayKhew','[email protected]',0198829387,'12/07/2011',NULL);INSERTINTO`Students`(ìd`,`studentName`,`gender`,`birthDate`,`mNo`,`contactName`,`contactEmail`,`contactPhone`,`startDate`,`remarks`)VALUES('s002','JoeBiden','m','13/03/2003','nm','LaylaBiden','[email protected]',0199283763,'14/05/2011',NULL);INSERTINTO`Students`(ìd`,`studentName`,`gender`,`birthDate`,`mNo`,`contactName`,`contactEmail`,`contactPhone`,`startDate`,`remarks`)VALUES('s003','BobBuilder','m','14/02/2002','LK920K','MamaBuilder','[email protected]',0167728376,'29/02/2012',NULL);INSERTINTO`Students`(ìd`,`studentName`,`gender`,`birthDate`,`mNo`,`contactName`,`contactEmail`,`contactPhone`,`startDate`,`remarks`)VALUES('s004','KennyKoh','m','18/02/1999','MM992','LisaKoh','[email protected]',0123160231,'19/01/2012',NULL);INSERTINTO`Students`(ìd`,`studentName`,`gender`,`birthDate`,`mNo`,`contactName`,`contactEmail`,`contactPhone`,`startDate`,`remarks`)VALUES('s005','JaneDoe','f','29/09/1999','nm','JackieDoe','[email protected]',0127736254,'02/03/2012',NULL);INSERTINTO`Students`(ìd`,`studentName`,`gender`,`birthDate`,`mNo`,`contactName`,`contactEmail`,`contactPhone`,`startDate`,`remarks`)VALUES('s006','LolaLai','f','02/05/2004','nm','MarkLai','[email protected]',0198827365,'11/09/2011',NULL);

COMMIT;-----------------------------------------------------Datafortable`Schedule`-----------------------------------------------------STARTTRANSACTION;INSERTINTO`Schedule`(`lesson_id`,`day`,`branch`,`level`,`time`,àe`)VALUES('sat1_s4','Sat','Sunway','basic','4pm','Aini');INSERTINTO`Schedule`(`lesson_id`,`day`,`branch`,`level`,`time`,àe`)VALUES('sat1_s5','Sat','Sunway','basic','5pm','Aini');INSERTINTO`Schedule`(`lesson_id`,`day`,`branch`,`level`,`time`,àe`)VALUES('sat1_s6','Sat','Sunway','basic','6pm','Aini');INSERTINTO`Schedule`(`lesson_id`,`day`,`branch`,`level`,`time`,àe`)VALUES('sat2_s4','Sat','Sunway','advance','4pm','Nina');INSERTINTO`Schedule`(`lesson_id`,`day`,`branch`,`level`,`time`,àe`)VALUES('sat2_s5','Sat','Sunway','advance','5pm','Nina');INSERTINTO`Schedule`(`lesson_id`,`day`,`branch`,`level`,`time`,àe`)VALUES('sat3_s6','Sat','Sunway','pre-comp','6pm','Marcus');

COMMIT;-----------------------------------------------------Datafortable`Link`-----------------------------------------------------STARTTRANSACTION;

INSERTINTO`Link`(`link_id`,ìd`,`lesson_id`)VALUES('L001','s001','sat1_s4');INSERTINTO`Link`(`link_id`,ìd`,`lesson_id`)VALUES('L002','s002','sat1_s5');INSERTINTO`Link`(`link_id`,ìd`,`lesson_id`)VALUES('L003','s003','sat1_s6');INSERTINTO`Link`(`link_id`,ìd`,`lesson_id`)VALUES('L004','s004','sat2_s4');INSERTINTO`Link`(`link_id`,ìd`,`lesson_id`)VALUES('L005','s005','sat1_s5');

COMMIT;--------------------------------------------

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