MELJUN CORTES Structured Query Language Complete

Chapter 5Chapter 5Structured Query Structured Query Language (SQL)Language (SQL)

MELJUN CORTESMELJUN CORTES

MELJUN CORTES, MBA,MPA,BSCS 2MELJUN CORTES ( CSSD04C4) SQL

In this chapter, you will In this chapter, you will learn:learn:

The basic commands and The basic commands and functions of SQLfunctions of SQL

How SQL is used for data How SQL is used for data manipulation (to add, modify, manipulation (to add, modify, delete, and retrieve data)delete, and retrieve data)

How to use SQL to query a How to use SQL to query a database to extract useful database to extract useful informationinformation


In this chapter, you will In this chapter, you will learn:learn:

How SQL is used for data How SQL is used for data administration (to create tables, administration (to create tables, indexes, and views)indexes, and views)

About more advanced SQL About more advanced SQL features such as updatable views, features such as updatable views, stored procedures, and triggersstored procedures, and triggers


Introduction to SQLIntroduction to SQL Ideal database languageIdeal database language

Create database and table structuresCreate database and table structures Perform basic data management Perform basic data management

chores (add, delete, and modify)chores (add, delete, and modify) Perform complex queries to Perform complex queries to

transform data into useful transform data into useful informationinformation


Introduction to SQLIntroduction to SQL SQL is the ideal DB languageSQL is the ideal DB language

Data definition languageData definition language (create (create tables and define access right to tables and define access right to tables)tables)

Data manipulation languageData manipulation language (update (update and manipulate data within database and manipulate data within database tables)tables)


Good Reasons to Study Good Reasons to Study SQLSQL

Easy to learnEasy to learn Portable to many database Portable to many database

specification, only minor specification, only minor differences among various SQLs differences among various SQLs defined in Oracle, SQL server, defined in Oracle, SQL server, DB2, Informix, Access, my SQL, …DB2, Informix, Access, my SQL, …


Good Reasons to Study Good Reasons to Study SQLSQL

ANSI standardization effort led to ANSI standardization effort led to de de factofacto query standard for relational query standard for relational database (SQL-99 or SQL3)database (SQL-99 or SQL3)

Forms basis for present and future Forms basis for present and future DBMS integration effortsDBMS integration efforts

Becomes catalyst in development of Becomes catalyst in development of distributed databases and database distributed databases and database client/server architectureclient/server architecture


Data Definition Data Definition CommandsCommands

Database modelDatabase model PRODUCT and PRODUCT and

VENDORVENDOR




Create database structureCreate database structure Holds all tables and is a collection of Holds all tables and is a collection of

physical files stored on diskphysical files stored on disk DBMS automatically creates tables to store DBMS automatically creates tables to store

metadatametadata Schema: a group of database objects (tables, Schema: a group of database objects (tables,

indexes and relationships)indexes and relationships) Database administrator creates structure or Database administrator creates structure or

schemaschema Logical group of tables or logical databaseLogical group of tables or logical database Groups tables by ownerGroups tables by owner Enforces securityEnforces security



ANSI standard to create ANSI standard to create database schemadatabase schema

CREATE SCHEMA AUTHORIZATION <creator>

Example:CREATE SCHEMA AUTHORIZATION JONES


Data Dictionary TableData Dictionary Table



Creating Table Creating Table StructureStructure

Data TypesData Types Number:Number:

NUMBER(L,D)NUMBER(L,D) INTEGERINTEGER SMALLINTSMALLINT DECIMAL(L,D)DECIMAL(L,D)

Character:Character: CHAR(L)CHAR(L) VARCHAR(L)VARCHAR(L)



Data TypesData Types DateDate

DATEDATE OthersOthers

TIMETIME TIME-STAMPTIME-STAMP REALREAL DOUBLEDOUBLE FLOATFLOAT ODLODL ……



Tables store end-user dataTables store end-user data May be based on data dictionary May be based on data dictionary

entriesentriesCREATE TABLE <table name>( <attribute1 name and attribute1 characteristics, attribute2 name and attribute2 characteristics, attribute3 name and attribute3 characteristics, primary key designation, foreign key designation and foreign key requirement>);


Example:Example:

CREATE TABLE VENDOR ( V_CODE INTEGER NOT NULL UNIQUEV_NAME VARCHAR(35) NOT NULLV_CONTACT VARCHAR(15) NOT NULLV_AREACODE CHAR(3) NOT NULLV_PHONE CHAR(8) NOT NULLV_STATE CHAT(2) NOT NULLV_ORDER CHAR(1) NOT NULLPRIMARY KEY(V_CODE) );


Example:Example:

CREATE TABLE PRODUCT ( P_CODE VARCHAR(10) NOT NULL UNIQUEP_DESCRIPT VARCHAR(35) NOT NULLP_INDATE DATE NOT NULLP_ONHAND SMALLINT NOT NULLP_MIN SMALLINT NOT NULLP_PRICE NUMBER(8,2) NOT NULLP_DISCOUNT NUMBER(5,2) NOT NULLV_CODE INTEGERPRIMARY KEY(P_CODE) FOREIGN KEY(V_CODE) REFERENCES VENDORON DELETE RESTRICTON UPDATE CASCADE);

Can not delete vendor tableYou can change vendor’s code


Using DomainsUsing Domains Domain is set of permissible values for a columnDomain is set of permissible values for a column Definition requires:Definition requires:

NameName Data typeData type Default valueDefault value Domain constraint or conditionDomain constraint or condition

CREATE DOMAIN <domain_name> AS DATA_TYPE[DEFAULT <default_value>][CHECK (<condition>)]


Using DomainsUsing Domains Example:Example:

You can use domain name instead of attribute’s You can use domain name instead of attribute’s data type, when you define a new tabledata type, when you define a new table

CREATE DOMAIN MARITAL_STATUS AS VARCHAR(8) AS DATA_TYPECHECK (VALUE IN (‘Single’, ‘Married’, ‘Divorced’, ‘Widowed’));

CREATE TABLE EMPLOYEE (EMP_NUM INTEGER NOT NULL CONSTRAIN EMPKRY KEY (EMP_NUM),EMP_LNAME VARCHAR(15) NOT NULL,EMP_FNAME VARCHAR(15) NOT NULL,EMP_STATUS MARITAL_STATUS NOT NULL);


Using DomainsUsing Domains Draw domain values from other Draw domain values from other

tables by including a SELECT tables by including a SELECT statement int eh CHECK clausestatement int eh CHECK clause

CREATE DOMAIN DISCOUNTING_RATES AS NUMBER(5,2)CHECK (VALUE IN (SELECT DISCOUNT FROM DISCOUNTBL);

DISCOUNT attributes in DISCOUNTBL table


Using DomainsUsing Domains Delete domainDelete domain

Not all database support create domain like Oracle Not all database support create domain like Oracle DROP DOMAIN <domain_name> [RESTRICT |CASCADE]

DROP DOMAIN MARITAL_STATUS CASCADE;

Prevent deleting until no attributes based on the domain

Change data type to the one defined In domain’s definition


SQL Integrity SQL Integrity ConstraintsConstraints

Adherence to Adherence to entity integrityentity integrity and and referential integrityreferential integrity rules is crucial rules is crucial Entity integrity enforced automatically if Entity integrity enforced automatically if

primary key specified in CREATE TABLE primary key specified in CREATE TABLE command sequencecommand sequence

Referential integrity can be enforced in Referential integrity can be enforced in specification of FOREIGN KEYspecification of FOREIGN KEY

Other specifications to ensure conditions met:Other specifications to ensure conditions met: ON DELETE RESTRICTON DELETE RESTRICT ON UPDATE CASCADEON UPDATE CASCADE


CREATE TABLE PRODUCT ( P_CODE VARCHAR(10) NOT NULL UNIQUEP_DESCRIPT VARCHAR(35) NOT NULLP_INDATE DATE NOT NULLP_ONHAND SMALLINT NOT NULLP_MIN SMALLINT NOT NULLP_PRICE NUMBER(8,2) NOT NULLP_DISCOUNT NUMBER(5,2) NOT NULLV_CODE INTEGERPRIMARY KEY(P_CODE) FOREIGN KEY(V_CODE) REFERENCES VENDORON DELETE RESTRICTON UPDATE CASCADE);

Some database does this Some database does this automatically without explicit automatically without explicit specificationsspecifications


Data Manipulation Data Manipulation CommandsCommandsCommon SQL CommandsCommon SQL Commands

Table 5.3


Data Entry and SavingData Entry and Saving Enters data into a tableEnters data into a table

INSERT INTO <table name> VALUES (attribute 1 value, attribute 2 value, … etc.);

INSERT INTO VENDORVALUES (21225, ‘my company’, ‘jun ni’, ‘319’,’232-2194’,’IA’,’Y’);


Data Entry and SavingData Entry and Saving

Use form (GUI) to enter dataUse form (GUI) to enter data


Data Entry and SavingData Entry and Saving

Saves changes to diskSaves changes to disk

COMMIT <table names> ;


Listing Table Contents Listing Table Contents and Other Commandsand Other Commands

Allows table contents to be listedAllows table contents to be listedSELECT <attribute names> FROM <table names>;

SELECT * FROM PRODUCT;SELECT P_CODE, P_DESCRIPT, P_INDATE, P_ONANG, P_MIN, P_PRICE, P_DISCOUNT, V_CODE FROM PRODUCT;




UPDATE command makes data UPDATE command makes data entry correctionsentry corrections

UPDATE PRODUCT SET P_INDATE=’01/18/2003’ WHERE P_CODE=’13-Q2/P2’



ROLLBACK command restores ROLLBACK command restores database back to previous database back to previous condition if COMMIT hasn’t been condition if COMMIT hasn’t been usedusedROLLBACK;



DELETE command removes table DELETE command removes table rowrow

DELETE FROM PRODUCT WHERE P_CODE=‘2238/QPD’;

DELETE FROM PRODUCT WHERE P_MIN=5;

5 ROWS ARE DELETED


QueriesQueries Creating partial listings of table Creating partial listings of table

contentscontentsSELECT <column(s)>FROM <table name>WHERE <conditions>;

Table 5.4 Mathematical Operators


ExamplesExamples

Mathematical Mathematical operatorsoperatorsSELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODE

FROM PRODUCTWHERE V_CODE = 21344;



ExamplesExamples

Mathematical Mathematical operatorsoperatorsSELECT P_DESCRIPT, P_INDATE, P_PRICE, V_CODEFROM PRODUCTWHERE V_CODE <> 21344;

Not equal


ExamplesExamples

Mathematical Mathematical operatorsoperatorsSELECT P_DESCRIPT, P_ONHAND, P_MIN, P_PRICE

FROM PRODUCTWHERE P_PRICE<=10;


ExamplesExamples Mathematical operators on Mathematical operators on

character attributescharacter attributes

Mathematical operators on datesMathematical operators on dates

SELECT P_CODE,P_DESCRIPT,P_ONHAND,P_MIN,P_PRICEFROM PRODUCTWHERE P_CODE < ‘1558-QWI’;

SELECT P_DESCRIPT,P_ONHAND,P_MIN,P_PRICE,PINDATEFROM PRODUCTWHERE P_INDATE >= ‘01/20/2002’;



Computed Columns Computed Columns New columns can be created New columns can be created

through valid computations or through valid computations or formulasformulas Formulas may contain mathematical Formulas may contain mathematical

operatorsoperators May contain attributes of any tables May contain attributes of any tables

specified in FROM clausespecified in FROM clause Alias is alternate name given to Alias is alternate name given to

table or column in SQL statementtable or column in SQL statementSELECT P_DESCRIPT,P_ONHAND,P_PRICE,P_ONHAND*P_PRICE AS TOTVALUE FROM PRODUCT;




OperatorsOperators

Logical: AND, OR, Logical: AND, OR, NOTNOT

SELECT *FROM PRODUCTWHERE V_CODE = 21344 OR V_CODE = 24288;


OperatorsOperators Rules of precedenceRules of precedence

Conditions within parenthesis Conditions within parenthesis executed firstexecuted first

Boolean algebraBoolean algebraSELECT *P_DESCRIPT, P_INDATE, P_PRICE, V_CODE FROM PRODUCTWHERE (P_PRICE<50 AND P_INDATE>’01/05/2002’) OR V_CODE=24288;




SpecialSpecial Operators Operators BETWEEN - defines limitsBETWEEN - defines limits

IS NULL - checks for nullsIS NULL - checks for nulls

SELECT * FROM PRODUCT WHERE P_PRICE BETWEEN 500.00 AND 100.00;

SELECT P_CODE, P_DESCRIPT FROM PRODUCT WHERE P_MIN IS NULL;


SpecialSpecial Operators Operators LIKE - checks for similar string LIKE - checks for similar string

(wildcard)(wildcard)SELECT V_NAME, V_CONTACT, V_AREACODE, V_PHONEFROM VENDOR WHERE V_CONTACT LIKE ‘Smith%’;


SpecialSpecial Operators Operators

IN - checks for value in a set IN - checks for value in a set

SELECT * FROM PRODUCT WHERE V_CODE=21344 OR V_CODE=24288;

SELECT * FROM PRODUCT WHERE V_CODE IN (21344,24288);

MORE EFFICIENTLY


SpecialSpecial Operators Operators

EXISTS – NOT NULLEXISTS – NOT NULL

DELETE FROM PRODUCT WHERE P_CODE EXISTS;

SELECT FROM PRODUCT WHERE V_CODE EXISTS;

SELECT FROM PRODUCT WHERE V_CODE IS NOT NULL;


Advanced Data Advanced Data ManagementManagementCommandsCommands ALTER - changes table structureALTER - changes table structure

ADD - adds columnADD - adds column MODIFY - changes column MODIFY - changes column

characteristicscharacteristicsALTER TABLE <table name>ADD (<column name> <new column characteristics>);

ALTER TABLE <table name>MODIFY (<column name> <new column characteristics>);


Advanced Data Advanced Data ManagementManagementCommandsCommands

ALTER - changes table structureALTER - changes table structure ADD - adds columnADD - adds column MODIFY - changes column MODIFY - changes column

characteristicscharacteristics



Changing a column’s data type:Changing a column’s data type:

Changing attribute characteristicsChanging attribute characteristics

ALTER TABLE PRODUCT MODIFY (V_CODE CHAR(5));

CHANGE FROM INTEGER TO CHAARCTERS

ALTER TABLE PRODUCT MODIFY (P_PRICE DECIMAL(9,2));

Increase width of P_PRICE



Adding a column to the table:Adding a column to the table:

Dropping (delete) a column from Dropping (delete) a column from the table:the table:

ALTER TABLE PRODUCT ADD ( P_SALECODE CHAR(1));

ALTER TABLE VENDOR DROP COLUMN V_ORDER;

Add column named P_SALECODE to PRODUCT table


Advanced Data Advanced Data Management Commands Management Commands

(con’t.)(con’t.) Entering data into Entering data into

new columnnew column Update entries:Update entries: UPDATE PRODUCT

SET P_SALECODE=‘2’ WHERE P_CODE=‘1546-qq2’;



(con’t.)(con’t.) Entering data into Entering data into

new columnnew column

UPDATE PRODUCTSET P_SALECODE=‘1’ WHERE P_CODE IN (‘2232/QWE’, ‘2232/QTY’);




(con’t.)(con’t.)UPDATE PRODUCTSET P_SALECODE=‘2’ WHERE P_INDATE<’12/25/2001’;

UPDATE PRODUCTSET P_SALECODE=‘1’ WHERE P_INDATE>’01/16/2002 AND P_INDATE<’01/21/2002’;



Advanced Data Advanced Data Management Management

Commands (con’t.)Commands (con’t.) Arithmetic operators and rules of Arithmetic operators and rules of precedenceprecedence

Table 5.5



Commands (con’t.)Commands (con’t.) Arithmetic operators and rules of Arithmetic operators and rules of precedenceprecedence

UPDATE PRODUCT SET P_ONHAND=P_ONHAND+20 WHERE P_CODE=‘2232/QWE’;

UPDATE PRODUCT SET P_PRICE=P_PRICE*1.10 WHERE P_PRICE<50.00;



Commands (con’t.)Commands (con’t.) Copying parts of tablesCopying parts of tables Copy the contents of selected table Copy the contents of selected table

columns with data values columns with data values

INSERT INTO <receiving table> <receiving table’s column names>SELECT <column names of the columns to be copied>FROM <contributing table name>;



Commands (con’t.)Commands (con’t.) Copying parts of tablesCopying parts of tables

CREATE TABLE (PARTPART_CODE CHAR(8) NOT NULL UNIQUE,PART_DESCRIPT CHAR(35)PART_PRICE DECIMAL(8,2),PRIMARY KEY (PART_CODE));

NEW TABLE NAME

INSERT INTO PART (PART_CODE,PART_DESCRIPT, PART_PRICE)SELECT P_CODE, P_DESCRIPT, P_PRICE FROM PRODUCT;

SELECT * FROM PART;




Commands (con’t.)Commands (con’t.) Deleting a table from databaseDeleting a table from database

DROP TABLE PART;



Commands (con’t.)Commands (con’t.) Primary and foreign key Primary and foreign key

designationdesignationALTER TABLE LINEADD PRIMARY KEY (INV_NUMBER, LINE_NUMBER)ADD FOREIGN KEY (INV_NUMBER) REFERENCES INVOICEADD FOREIGN KEY (PROD_CODE) REFERENCES PRODUCT;



Commands (con’t.)Commands (con’t.) Primary and foreign key Primary and foreign key

designationdesignationALTER TABLE PRODUCT ADD PRIMARY KEY (P_CODE);

ALTER TABLE PRODUCT ADD FOREIGN KEY (V_CODE) REFERENCES VENDOR;


More complex queries More complex queries and sql functionsand sql functions

Ordering listing: list in special Ordering listing: list in special order (ascending order to order (ascending order to descending order)descending order)ORDER BY <attributes>

ORDER BY <attributes> DESC

ascending

descending

SELECT P_CODE, P_DESCRIPT, P_INDATE, P_PRICE FROM PRODUCT ORDER BY P_PRICE;




Cascading order sequenceCascading order sequence

ORDER BY <attribute1 attribute2, …>

ORDER BY <attribute1, attribute2, …> DESC

SELECT EMP_LNAME, EMP_FNAME, EMP_INITIAL, EMP_AREACODE, EMP_PHONE

FROM EMPLOYEEORDER BY EMP_LNAME, EMP_FNAME, EMP_INITIAL;





Use order by clause in Use order by clause in conjunction with other SQL conjunction with other SQL commandscommandsSELECT P_DESCRIPT, V_CODE, P_INDATE, P_PRICE FROM PRODUCT WHERE P_INDATE<’01/21/2002’ AND P_PRICE<=50.00ORDER BY V_CODE, P_PRICE DESC;




List unique valuesList unique values

SELECT DISTINCT V_CODE FROM PRODUCT;


AggregateAggregate Function Operations Function Operations



COUNT (count raw numbers for a COUNT (count raw numbers for a given column)given column)

SELECT COUNT(DISTINCT V_CODE)FROM PRODUCT;

SELECT COUNT(DISTINCT V_CODE)FROM PRODUCTWHERE P_PRICE <= 10.00;



MAX and MINMAX and MIN

SELECT MIN(P_PRICE)FROM PRODUCT;

SELECT P_CODE, P_DESCRIPT, P_PRICEFROM PRODUCTWHERE P_PRICE = MAX(P_PRICE);


Example Aggregate Example Aggregate Function Operations Function Operations

(con’t.)(con’t.) SUMSUM

AVGAVG

SELECT SUM(P_ONHAND * P_PRICE)FROM PRODUCT;

SELECT P_DESCRIPT, P_ONHAND, P_PRICE, V_CODEFROM PRODUCTWHERE P_PRICE > (SELECT AVG(P_PRICE) FROM PRODUCT)ORDER BY P_PRICE DESC;


Grouping dataGrouping data Creates frequency distributionsCreates frequency distributions Only valid when used with SQL Only valid when used with SQL

arithmetic functionsarithmetic functions

HAVING clause operates like WHERE for HAVING clause operates like WHERE for grouping output grouping output

SELECT P_SALECODE, MIN(P_PRICE)FROM PRODUCT_2GROUP BY P_SALECODE;

SELECT V_CODE,COUNT(DISTINCT(P_CODE)),AVG(P_PRICE)FROM PRODUCT_2GROUP BY V_CODEHAVING AVG(P_PRICE) < 10;


More Complex Queries More Complex Queries and and

SQL Functions (con’t.)SQL Functions (con’t.) Virtual tables: creating a viewVirtual tables: creating a view CREATE VIEW commandCREATE VIEW command Creates logical table existing only in Creates logical table existing only in

virtual memoryvirtual memory

SQL indexes SQL indexes

CREATE VIEW PRODUCT_3 ASSELECT P_DESCRIPT, P_ONHAND, P_PRICEFROM PRODUCTWHERE P_PRICE > 50.00;

CREATE INDEX P_CODEXON PRODUCT(P_CODE);


Joining database tablesJoining database tables Data are retrieved from more than one tableData are retrieved from more than one table

Recursive queries joins a table to itselfRecursive queries joins a table to itself

Outer joins can be used when ‘null’ values need to be Outer joins can be used when ‘null’ values need to be included in query result included in query result

SELECT PRODUCT.P_DESCRIPT, PRODUCT.P_PRICE, VENDOR.V_NAME, VENDOR.V_CONTACT, VENDOR.V_AREACODE, VENDOR.V_PHONEFROM PRODUCT, VENDORWHERE PRODUCT.V_CODE = VENDOR.V_CODE;

SELECT A.EMP_NUM,A.EMP_LNAME,A.EMP_MGR,B.EMP_LNAME FROM EMP A, EMP BWHERE A.EMP_MGR=B.EMP_NUMORDER BY A.EMP_MGR



Updatable ViewsUpdatable Views

Common operation in production Common operation in production environments is use of batch routines to environments is use of batch routines to update master table attributes using update master table attributes using transaction datatransaction data

Batch update routine pools the Batch update routine pools the transactions into a single “batch” to transactions into a single “batch” to update a master table field in a single update a master table field in a single operation.operation.

Overnight batch jobsOvernight batch jobs Not all views are updatableNot all views are updatable Example: master PRODUCT and product Example: master PRODUCT and product

monthly sales table (PMSALES)monthly sales table (PMSALES)



UPDATE PRODUCT, PMSALES SET PRODUCT.PROD_ QOH=PROD_QOH-PMS-QTY WHERE PRODUCT.PROD_ID=PMSALES.PROD_ID;

This works for ACCESS not for Oracle.

If you use Oracle, you need to create an updatable view.

Updatable view is a view that can be used to update attributes in base tables.


Updatable ViewsUpdatable Views RestrictionsRestrictions

GROUP BY expressions cannot be GROUP BY expressions cannot be usedused

Cannot use set operators---UNION, Cannot use set operators---UNION, INTERSECTION, etc.INTERSECTION, etc.

Most restrictions based on use of Most restrictions based on use of JOINS or group operators in viewsJOINS or group operators in views


Updatable ViewsUpdatable Views Create Updatable viewCreate Updatable view

Now you can use UPDATE command to Now you can use UPDATE command to update the viewupdate the view

CREATE VIEW MPSVUPD AS (SET PRODUCT.PROD_ID, PRODUCT.PROD_QOH, PMSALES.PMS_QTYFROM PRODUCT, MPSALES WHERE PRODUCT.PROD_ID=PMSALES.PROD_ID);

UPDATE PMSVUPDSET PROD_QOH=PROD_QOH-PSM-QTY


Procedural SQLProcedural SQL SQL is a declarative language, not SQL is a declarative language, not

support conditional executions of support conditional executions of procedures and looping executionsprocedures and looping executions

SQL shortcomingsSQL shortcomings Doesn’t support execution of stored Doesn’t support execution of stored

procedures based on logical conditionprocedures based on logical condition Fails to support looping operationsFails to support looping operations

The way to use logical or The way to use logical or procedural statements is to embed procedural statements is to embed SQL into programming languagesSQL into programming languages


Procedural SQLProcedural SQL SolutionSolution

Embedded SQL can be called from within procedural Embedded SQL can be called from within procedural programming languages.programming languages.

Using embedded SQL is still the most common Using embedded SQL is still the most common approach to maintaining procedural approach to maintaining procedural capabilities.capabilities.

Shared Code is isolated and used by all application Shared Code is isolated and used by all application programs.programs.

Procedural SQL (PL/SQL) stored within the database, Procedural SQL (PL/SQL) stored within the database, executed by DBMS, and invoked by the end userexecuted by DBMS, and invoked by the end user

TriggersTriggers Stored proceduresStored procedures PL/SQL functionsPL/SQL functions


Procedural SQL Procedural SQL (con’t.)(con’t.) Procedural SQL allows the use of Procedural SQL allows the use of

procedural code and SQL procedural code and SQL statements that are stored within statements that are stored within the database.the database.

The procedural code is executed The procedural code is executed by the DBMS when it is invoked by by the DBMS when it is invoked by the end user.the end user.


Procedural SQL Procedural SQL (con’t.)(con’t.)

End users can use procedural SQL End users can use procedural SQL (PL/SQL) to create:(PL/SQL) to create: TriggersTriggers Stored proceduresStored procedures PL/SQL functions (different from SQL PL/SQL functions (different from SQL

built-in functions)built-in functions)


TriggersTriggers Procedural SQL code invoked Procedural SQL code invoked

before or after data row is before or after data row is selected, inserted, or updatedselected, inserted, or updated

Associated with a database tableAssociated with a database table Table may have multiple triggersTable may have multiple triggers Executed as part of transactionExecuted as part of transaction


TriggersTriggers Can enforce particular constraintsCan enforce particular constraints Automate critical actions and Automate critical actions and

provide warnings for remedial provide warnings for remedial actionaction

Can update values, insert records, Can update values, insert records, and call proceduresand call procedures

Add processing powerAdd processing power


Triggers (con’t.)Triggers (con’t.) Oracle example Oracle example

CREATE OR REPLACE TRIGGER TRG_PRODUCT_REORDERAFTER INSERT OR UPDATE OF P_ONHAND ON PRODUCTBEGIN

UPDATE PRODUCTSET P_REORDER=1WHERE P_ONHAND<=P_MINEND;


Stored ProceduresStored Procedures Named collection of procedural and Named collection of procedural and

SQL statements stored in databaseSQL statements stored in database Invoked by nameInvoked by name Executed as unitExecuted as unit Invoked with EXECInvoked with EXEC Used in multiple-update transaction Used in multiple-update transaction

(entire contents of stored (entire contents of stored procedure will be transmitted and procedure will be transmitted and executed, which reduce network executed, which reduce network transfer delay.transfer delay.


Stored ProceduresStored Procedures Invoked with EXECInvoked with EXEC CREATE OR REPLACE PROCEDURE procedure_name (argument IN/OUT data-type, etc) IS/AS BEGIN

DECLARE variable name and data typePL/SQL or SQL statements;

END;

EXEC store_procedure_name (parameter, parameter, …)


Stored ProceduresStored Procedures ExampleExample

CREATE OR REPLACE PROCEDURE PROD_REORDER_SETAS BEGIN UPDATE PRODUCTSET P_REORDER=1 WHERE P_ONHAND <=P_MIN;UPDATE PRODUCTSET P_REORDER=0 WHERE P_ONHAND>_MIN;END;

EXEC PROD_REORDER_SET;


Stored ProceduresStored Procedures ExampleExample CREATE OR REPLACE PROCEDURE PROD_SALE(CODE IN VARCHAR2, QTYSOLD IN NUMBER)AS BEGIN UPDATE PRODUCT SET P_REORDER=P_ONHAND-QTYSOLD; WHERE P_CODE=CODE;END;

EXEC PROD_SALE(‘22232/QTY’,3);


PL/SQL Stored FunctionsPL/SQL Stored Functions

Named group of procedural and Named group of procedural and SQL statements that returns a SQL statements that returns a valuevalueCREATE FUNCTION function_name (argument IN data-type, etc)RETURN data-typeAS BEGIN

PL/SQL statements;RETURN (value); ……

END;


PL/SQL Stored FunctionsPL/SQL Stored Functions

Invoked from within stored Invoked from within stored procedures or triggersprocedures or triggers

Cannot be invoked from within Cannot be invoked from within SQL statementsSQL statements

CREATE FUNCTION function_name (argument IN data-type, etc)RETURN data-typeAS BEGIN

PL/SQL statements;RETURN (value); ……

END;


Converting an ER model Converting an ER model into a database structureinto a database structure Require the some rulesRequire the some rules Database of artistDatabase of artist

A painter may have many paintings A painter may have many paintings (1:M)(1:M)

Each painter painted by one and only Each painter painted by one and only one painter (so far it is a 1:M) one painter (so far it is a 1:M) relationships between PAINTER and relationships between PAINTER and PAINTINGPAINTING

A painter must have at least painting A painter must have at least painting (cardinality is (1:N)(cardinality is (1:N)

A painting might (or might not) be A painting might (or might not) be exhibited in a gallery (another Table, exhibited in a gallery (another Table, which is optional to the paining entity)which is optional to the paining entity)


Artist Database ERD Artist Database ERD and Tablesand Tables

Figure 5.55



Table Structure and Table Structure and specific requirementsspecific requirements

PAINTER(PTR_NUM, PTR_LASTNAME,PTR_FIRSTNAME, PTR)INITIAL, PTR_AREACODE, PTR_PHONE)

GALLERY(GAL_NUM,GAL_OWNER, GAL_AREACODE, GAL_PHONE, GAL_RATE)

PAINTING(PNTG_NUM, PNTG_TITLE, PNTG_PRICE, PNTG_NUM, GAL_NUM)


Further action Further action considerationsconsiderations

1. Delete raw of painter will effect the PAINTER’s table and cerate delete anomaly. Impose a DELETE RESTRICT on PAINTER’s table

2. No problem to add raw in PAINTER”s table

3. Change PRT_NUM (primary key) will affects other tables. Make sure we need to create a trigger to automatically take care the case. Use UPDATE CASCADE (all foreign key references to primary key are updated when the primary key is changed)

4. Delete GAL_NUM may cause problem, unless we impose DELETE RESTRICT on GALLERY table.

5. No problem to add GALEERY raw

6. UPDATE CASCADE is used for GALEERY table


Creates Tables using Creates Tables using SQLSQL

CREATE TABLE PAINTER (PTR_NUM CHAR(4) NOT NULL UNIQUE,PTR_LASTNAME CHAR(15) NOT NULL,PTR_FIRSTNAME CHAR(15) NOT NULL,PTR_INITIAL CHAR(1),PTR_AREACODE CHAR(3),PTR_PHONE CHAR(8),PRIMARY KEY(PTR_NUM));



CREATE TABLE GALLERY (GAL_NUM CHAR(4) NOT NULL UNIQUE,GAL_OWNER CHAR(35) NOT NULL,GAL_AREACODE CHAR(3),GAL_PHONE CHAR(8) NOT NULL,GAL_RATE NUMBER(4,2),PRIMARY KEY(GAL_NUM));



CREATE TABLE GALLERY (GAL_NUM CHAR(4) NOT NULL UNIQUE,GAL_OWNER CHAR(35) NOT NULL,GAL_AREACODE CHAR(3),GAL_PHONE CHAR(8) NOT NULL,GAL_RATE NUMBER(4,2),PRIMARY KEY(GAL_NUM));



CREATE TABLE PAINTING (PNTG_NUM CHAR(4) NOT NULL UNIQUE,PNTG_TITLE CHAR(35) NOT NULL,PNTG_PRICE NUMBER(9,2),PTR_NUM CHAR(4) NOT NULL,GAL_NUM CHAR(4)PRIMARY KEY(GAL_NUM));

FOREIGN KEY (PTR_NUM) REFERENCES PAINTERON DELETE RESTRICTON UPDATE CASCADE,

FOREIGN KEY (GAL_NUM) REFERENCES GALLERYON DELETE RESTRICTON UPDATE CASCADE,


General Rules General Rules Governing Governing

Relationships Among Relationships Among TablesTables

SQL statement associated with the combination of

Optional and mandatoryVs.Relationships (N:M, 1:M, 1:1)




Figure 5.57: M:N, Both Sides Optional

Figure 5.56: M:N, Both Sides Mandatory


General Rules Governing General Rules Governing Relationships Among Relationships Among

TablesTables

Figure 5.58: M:N, One Side Optional

Figure 5.59: 1:M, Both Sides Mandatory



TablesTables






Figure 5.59: 1:M, Both Sides Mandatory



TablesTables

Figure 5.60: 1:M, Both Sides Optional

Figure 5.61: 1:M, Many Side Optional, One Side Mandatory




Figure 5.62: 1:M, One Side Optional, One Side Mandatory

Figure 5.63: 1:1, Both Sides Mandatory




Figure 5.64: 1:1, Both Sides Optional

Figure 5.65: 1:1, One Side Optional, One Side Mandatory




Figure 5.66: Weak Entity, Foreign Key Located in Weak Entity

Figure 5.67: Multivalued Attributes (New Table in 1:M Relationship, Foreign Key CAR_VIN in the New Table

Technology

MELJUN CORTES Structured Query Language Complete