Microsoft Client Virtualization Strategy White Pape

8/12/2019 Microsoft Client Virtualization Strategy White Pape

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Data Provider

? Provides and "aintains lin5 to database

+ight#eight

)et of related co"ponents

o /onnection

? actual connection to D6

.NET provides t#o providers ! ),+ )erver and O+E D6

? ),+ )erver "uch lighter than O+E D6

? 7nfo re$uired for connection stored in /onnection)tring

propert

? )i"ilar to previous O+E D6 version

Onl set #hen connection closed

ust al#as specif server %can be set to local&

)ecurit info %e.g. pass#ord& not returned unless 8Persist )ecurit 7nfo = true9 present

Argu"ent E4ception generated if /onnection)tring cannot be parsed

Dont need to specif provider %e.g. ),+O+ED6& if using )$l/onnection

Avoid using ;D+ %;niversal Data +in5& files as parsed ever ti"e connection opened

%because file "a have changed& ! use static connection string? Auto"aticall pooled

? sste" #ill reuse e4isting connection if

/onnection)tring "atches and not currentl in use %i.e.

/lose%& or Dispose%& has been called&

connection re"oved if lifeti"e e4pired or connection severed

? 'aises ( events related to connection state

? 7nfoessage !


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o /o""and

? E4ecute D6 co""ands across /onnection

.NET provides t#o providers ! ),+ )erver and O+E D6

/onstructor ta5es optional args

? ),+ state"ent to e4ecute at data source

/onnection ob2ectTransaction ob2ect

? E4ecuteNon,uer ! e4ecute co""ands #ith no return values*

e.g. Data Definition +anguage DD+ state"ents li5e /'EATE

TA6+E and so"e )Ps

E4ecute)calar ! e4ecute co""ands returning single value %value of first colu"n of

first ro# in result set&

E4ecute'eader ! retrieve result as strea" of data via Data'eader ob2ect

properties represent database co""ands

? )elect/o""and ! contains co""and te4t or ob2ect to

select data fro" db. E4ecuted #hen Fill "ethod called.

7nsertco""and ! contains co""and te4t or ob2ect to insert data into table.

Delete/o""and ! contains co""and te4t or ob2ect to delete ro# fro" table.

;pdate/o""and ! contains co""and te4t or ob2ect to update data in db.

Use subject to ourTer"s and /onditions Written By 'oss Fruen
http://www.gsys.biz/Documents/Downloads/MCP/70-316http://www.gsys.biz/Documents/Downloads/MCP/70-316http://www.gsys.biz/homepages/rfruen/http://www.gsys.biz/homepages/rfruen/http://www.gsys.biz/Documents/Downloads/MCP/70-316


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DataReader Vs DataSet

? ;se Data)et for follo#ing

o 'e"ote data bet#een tiers or fro" -+


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myConnection.ConnectionString =Provider=Microsoft.Jet.O!D".#.$;D%t%So&rce=C'ort*wind.mdb+;

Using Command? Do not re$uire DataAdapter to interact #ith D6

/reate:

o Drag stored procedure fro" )erver E4plorer to designer

Drag )$l/o""and OleDb/o""and fro" data tab or toolbo4

Declare and instantiate instance of /o""and ob2ect

? /o""andTpe propert indicates its tpe

o Te4t ! /o""andTe4t contains ),+ $uer

)toredProcedure ! /o""andTe4t contains na"e of )P

TableDirect ! na"e of table%s& indicated b /o""andTe4t. 'eturns all colu"ns and

ro#s of specified tables

? )et /onnection propert to active connection

Para"eters are values that fill placeholders in co""and te4t at run ti"e* stored in

Para"eters propert and read at runti"e

S,lConnection nwindConn = new S,lConnection(-D%t%So&rce=loc%l*ost;ntegr%ted Sec&rity=SSP;niti%lC%t%log=nort*wind-);

S,lComm%nd s%lesCMD = new S,lComm%nd(-S%les"yC%tegory-/ nwindConn);s%lesCMD.Comm%nd0y1e = Comm%nd0y1e.StoredProced&re;

S,lP%r%meter myP%rm = s%lesCMD.P%r%meters.2dd(-3C%tegory%me-/S,lDb0y1e.4%rC*%r/ 56);myP%rm.4%l&e = -"ever%ges-;

nwindConn.O1en();

S,lD%t%7e%der my7e%der = s%lesCMD.!8ec&te7e%der();

Console.9riteine(-:$/ :5-/ my7e%der.


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Para"eterNa"e ! na"e to be used as 5e in code %if not using ordinal&

Precision ! "a4i"u" nu"ber of digits in value %nu"eric and deci"al&

)cale ! nu"ber of deci"al places in value %nu"eric and deci"al&

)ie ! "a4i"u" sie of data in colu"n %string and binar&

)ource/olu"n ! colu"n to loo5 up or "ap values

)ourceBersion ! version of colu"n to use #hen editingBalue ! Balue represented b para"eter

? /an provide /o""and6ehavior argu"ent to e4tract 6+O6s fro" database.

)et to /o""and6ehavior.)e$uentialAccess and use Cet6tes%& to access data.

ust retrieve data in order presented ! once reader steps beond that colu"n

it is no longer available

S,lConnection 1&bsConn = new S,lConnection(-D%t%So&rce=loc%l*ost;ntegr%ted Sec&rity=SSP;niti%l C%t%log=1&bs;-);S,lComm%nd logoCMD = new S,lComm%nd(-S!!C0 1&b>id/ logo ?7OM1&b>info-/ 1&bsConn);

?ileStre%m fs; @@ 9rites t*e "O" to % file@@ (A.bm1).

"in%ry9riter bw; @@ Stre%ms t*e "O" to t*e?ileStre%m obBect.

int b&fferSie = 5$$; @@ Sie of t*e "O" b&ffer.byteE o&tbyte = new byteb&fferSieE; @@ 0*e "O" byteE b&ffer to

@@ be filled by id = --; @@ 0*e 1&blis*er id to &se in@@ t*e file n%me.

@@ O1en t*e connection %nd re%d d%t% into t*e D%t%7e%der.1&bsConn.O1en();S,lD%t%7e%der my7e%der =logoCMD.!8ec&te7e%der(Comm%nd"e*%vior.Se,&enti%l2ccess);

w*ile (my7e%der.7e%d()):

@@ id = my7e%der.id F -.bm1-/ ?ileMode.O1enOrCre%te/?ile2ccess.9rite);

bw = new "in%ry9riter(fs);

@@ 7eset t*e st%rting byte for t*e new "O".

st%rtnde8 = $;



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o e.g. Cet6oolean%&

ust 5no# ordinal %doesnt #or5 #ith colu"n na"e&

/an retrieve ordinal fro" colu"n na"e using CetOrdinal%& "ethod

;seful if 5no# tpe of particular colu"n

? /an retrieve "ultiple result sets fro" single co""ando )et /o""andTpe of /o""and ob2ect to Te4t

)eparate ),+ state"ents using

Each ),+ state"ent e4ecuted se$uentiall* each result set returned separatel b

Data'eader

First result set returned auto"aticall fro" Data'eader

)ubse$uent result sets accessed b calling Ne4t'esult%& "ethod

do:

w*ile(my7e%der.7e%d())

:@@ oo1 t*ro&g* records of 7ecordSet

w*ile (my7e%der.e8t7es&lt());

? E4ecuting ad hoc ),+ $ueries

o First build co""and string

)et /o""andTe4t and /onnection properties for /o""and ob2ect at construction

string Cmd = D!!0! A ?7OM !m1loyees 9H!7!%me=I+ %String I+;

OleDbComm%nd myComm%nd = new OleDbComm%nd(Cmd/myConnection);

myConnection.O1en();myComm%nd.!8ec&teonK&ery();myConnection.Close();

? Obtain sche"a info about result using Cet)che"aTable%& "ethod. 'eturns

DataTable populated #ith sche"a for current result set. /ontains one ro# for

each colu"n in result set* each colu"n "aps to a propert of colu" returned

in result set #here /olu"nNa"e = na"e of propert and value is value of

propert

D%t%0%ble sc*em%0%ble = my7e%der.


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my7owmyColE);

Console.9riteine();

? Al#as call /lose%& "ethod #hen finished #ith Data'eader

Creating Data Adapters

? +in5 data source and Data)et @ providing functionalit to retrieve data*

populate Data)et and perfor" updates

anages e4change bet#een single DataTable in Data)et and data source. Data)et

fre$uentl contains "ultiple DataTables ! create DataAdapter for each DataTable

( pri"ar adapters

o )$lDataAdapter

OleDbAdapter

? /reate DataAdpter

o 6 )erver E4plorer

? Drag table fro" Data /onnection node of )erver E4plorer to

Designer


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Auto7ncre"ent)tep and Auto7ncr"ente "anuall. Fil)che"a%& is costl to

call ! if 5no# pri"ar@5e infor"ation at design ti"e then these should be set

e4plicitl to increase perfor"ance.

@@ Obt%in sc*em% vi% ?illSc*em%()

D%t%Set c&stDS = new D%t%Set();c&stD2.?illSc*em%(c&stDS/ Sc*em%0y1e.So&rce/ -C&stomers-);c&stD2.?ill(c&stDS/ -C&stomers-);

@@ Obt%in sc*em% vi% ?ill()D%t%Set c&stDS = new D%t%Set();c&stD2.MissingSc*em%2ction = MissingSc*em%2ction.2dd9it*ey;c&stD2.?ill(c&stDS/ -C&stomers-);

? Tableappings per"it use of colu"n na"es in DataTable different to those in

database* e.g. to create "apping called Authorsapping for the Authors

table use

worN2d%1ter.0%bleM%11ings.2dd(2&t*orsM%11ing+/ My2&t*ors+);

? 7f no "apping na"e is passed to Fill%& "ethod* then the DataAdapter #ill loo5

for "apping called 8Table9. 7f an colu"n is not present in "apping then it is

provided #ith default na"e of )ource/olu"nN %N being incre"ented&.

+i5e#ise if no table na"e provided then default na"e of )ourceTabeN is

used. Follo#ing creates default "apping:

D%t%0%bleM%11ing c&stM%1 = c&stD2.0%bleM%11ings.2dd(-0%ble-/-ort*windC&stomers-);

c&stM%1.Col&mnM%11ings.2dd( -Com1%ny%me-/ -Com1%ny-);

c&stM%1.Col&mnM%11ings.2dd( -Cont%ct%me-/ -Cont%ct-);c&stM%1.Col&mnM%11ings.2dd( -Post%lCode-/ -PCode-);

c&stD2.?ill(c&stDS);

? 7f )elect/o""and returns "ultiple tables* Fill #ill generate Table na"es #ith

incre"ental na"es starting fro" specified na"e. ;se table "appings to "ap

auto"aticall generated na"es to na"es #ant to use* e.g. follo#ing

)elect/o""and returns t#o tables that #ill be na"ed /usto"ers and

/usto"es3* "ap /usto"ers3 to Orders

c&stD2.0%bleM%11ings.2dd(-C&stomers5-/ -Orders-)c&stD2.?ill(c&stDS/ -C&stomers-)

Typed DataSets

? )tandard Data)et = #ee5l tped ! "ust convert data point fro" ob2ect to

desired tpe

Tped Data)et = strongl tped

7nstance of class derived fro" Data)et

/lass structure defined b -+ sche"a file %-)D& defining table na"es and tpes



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Dependence on -)D "eans onl use #here 5no# structure of data being used in

advance

/reate using Cenerate Dataset button in Data dialog bo4 ! generates -)D file and

optionall adds instance of Data)et to designer

Lesson 3

i!!ing DataSet "it#out DataAdapter

? /reate Data)et progra""aticall* and provide it #ith structure

D%t%Set myD%t%Set = new D%t%Set();

D%t%0%ble my0%ble = new D%t%0%ble();myD%t%Set.0%bles.2dd(my0%ble);

D%t%Col&mn 2cco&ntsCol&mn = newD%t%Col&mn(2cco&nts+);

myD%t%Set.0%bles$E.Col&mns.2dd(%cco&ntsCol&mn);

D%t%7ow my7ow;my7ow = myD%t%Set.0%bles$E.ew7ow();

for(int i=$; StringCollection.Co&nt; iFF):

my7ow.temco&nterE = StringCollection iE;

myD%t%Set.0%bles($).7ows.2dd(my7ow);

? Access Flat File and populate Data)et using progra""atic techni$ue outlined

above


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System.O.Stre%m7e%der my7e%der = newSystem.O.Stre%m7e%der(C'?ile.t8t+);

String myString;

w*ile (my7e%der.PeeN() R= 5):

myString = my7e%der.7e%dine();myD%t%Set.0%bles0%ble 5+E.7ows.2dd

(myString.S1lit(c*%r.P%rse(/+)));

Data Re!ation O$%ects

? 'epresents relationship bet#een t#o colu"ns in different tables #ithinData)et

/ontained in 'elations propert of Data)et

/reate b specifing na"e of Data'elation* parent colu"n and child colu"n

D%t%7el%tion my7el%tion = new D%t%7el%tion(D%t%7el%tion 5+/ col&mn5/ col&mnL);

myD%t%Set.7el%tions.2dd(my7el%tion);

? ;se to retrieve parent and child ro#s b calling Cet/hild'o#s or

CetParent'o# on Data'o# providing Data'elation as par"

D%t%s7owE C*ild7ows;D%t%7ow P%rent7ow;

@@ 7et&rn %ll c*ild rows of row 5 %s defined byC&stomersOrdersC*ild7ows =myD%t%Set.0%blesC&stomers+E.7ows5E.


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Foreign e ! rules used to update child ro#s #hen parent edited

? /reate ;ni$ue /onstraint

o Easiest is set ;ni$ue propert of Data'o# to true

/an create ;ni$ue/onstraint and "anuall add to /onstraints collection

Tni,&eConstr%int myConstr%int = newTni,&eConstr%int(myD%t%7ow);

myD%t%0%ble.Constr%ints.2dd(myConstr%int);

o /an specif "ultiple colu"ns

D%t%Col&mnE myCol&mns = new D%t%Col&mnLE;myCol&mns$E =

!m1loyees0%ble.Col&mns?irst%me+E;myCol&mns$E =

!m1loyees0%ble.Col&mns%st%me+E;Tni,&eConstr%int myConstr%int = new

Tni,&eConstr%int(myCol&mns);!m1loyees0%ble.Constr%ints.2dd(myConstr%int);

? /reate Foreign e /onstraint b specifing parent and child colu"ns and

adding to /onstraints collection of parent table

?oreigneyConstr%int myConstr%int = new?oreigneyConstr%int(C&stomers0bl.Col&mnsC&stomerD+E/ Orders0bl.Col&mnsC&stomerD+E);

C&stomers0bl.Constr%ints.2dd(myConstr%int);

? Foreigne/onstraint has rules e4posed as properties

o ;pdate'ule ! enforce #hen parent updated

Delete'ule ! enforce #hen parent deleted

Accept'e2ect'ule ! enforce #hen Accept/hanges "ethod of DataTable to #hich

constraint belongs is called

? )et rules to one of follo#ing values %default = /ascade&

o /ascade ! /hanges in parent cascaded to child ro#s

None ! changes in parent have no effect on child ro#s. a lead to child records

referencing invalid parents

)etDefault ! foreign 5e in child records set to its default value %see colu"ns

DefaultBalue propert&

)etNull ! foreign 5e in child table set to Null ! can result in invalid data #ithin

children

Editing Data

? Data)et "aintain ( versions of itself

o Original state



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/urrent state

?


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my0r%ns%ction =myConnection."egin0r%ns%ction();

U

my0r%ns%ction.Commit();c%tc*(!8ce1tion e8)

:mytr%ns%ction.7ollb%cN();

fin%lly:

myConnection.Close();

&and!ing Update Errors

? DataAdapter provides 'o#;pdate event that fires after update event but

before e4ception thro#n ! opportunit to handle errors #ithout resource@

intensive e4ception bloc5s

'o#;pdate provides 'o#;pdatedEventArgs that is used to deter"ine error that has

occurred and ho# to proceed

o /o""and ! co""and to e4ecute #hen perfor"ing update

Errors ! errors generated b Data Provider #hen co""and e4ecutes

'ecordsAffected ! nu"ber of records affected b e4ecution of co""and

'o# ! ro# updated

)tatus @ ;pdate)tatus of co""and

? Deter"ine if error occurred b e4a"ining )tatus.

o /ontinue ! no errors have occured

ErrorsOccured ! error occurred #hile atte"pting to update this ro#

)5ipAll'e"aining'o#s ! updates for current and subse$uent ro#s should be s5ipped

)5ip/urrent'o# ! update for current ro# should be s5ipped* but rest of updates

should proceed nor"all

? /an choose to handle error in 'o#;pdated event b setting )tatus propert to

so"ething other than ErrorsOccured

o Note* if set )tatus to /ontinue the DataAdapter #ill ignore the error

and continue but unpredictable results "a arise %safer to use)5ipAll'e"aining'o#s or )5ip/urrent'o#&

7f )tatus re"ains ErrorsOccured an e4ception thro#n

private void "DataAdapterG'o#;pdated% ob2ect sender*

)ste".Data.)$l/lient.)$l'o#;pdatedEventArgs e&

H

if%e.)tatus == ;pdate)tatus.ErrorsOccured&

H

I

e.)tatus = ;pdate)tatus.)5ip/urrent'o#



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J

J

Lesson 4

Data Binding

? 'elationship bet#een data provider and consu"er

E4a"ple = Te4t6o4 #hich displas colu"n in data source at current ro#. As ro#

changes* the value displaed changes

Data Providers

? Provides data to bound properties and controls

Note ! not a DataProvider %co"ponents providing disconnected database access&

An ob2ect i"ple"enting 7+ist can be data provider %includes arras and collections&anage data currenc %i.e. current record& through /urrencanager ob2ect

Data Consumers

? /an bind an run@ti"e accessible propert of an control to a data source

T#o tpes of binding

o )i"ple ! binds one record at a ti"e to a control

/o"ple4 ! binds "ultiple records si"ultaneousl to a control* e.g. bind +ist6o4 to a

colu"n in DataTable and it #ill displa all "e"bers of that colu"n

Create Simp!e $ound contro!

? ;se Data6indings propert %instance of /ontrol6indings/ollection&

Displaed as node in Properties #indo#* e4pands to sho# properties that are

co""onl data bound

To bind propert clic5 bo4 ne4t to it in Data6indings node and select desired provider

%Data)ets and DataBie#s can be e4panded to sho# DataTables that can be e4panded

to list available colu"ns

7f propert not listed in Data6indings clic5 Advanced bo4 follo#ed b Elipses %I&

#hich lists all run ti"e available properties

? At run@ti"e can add* re"ove or clear data binding info b setting appropriate

"e"ber of Data6indings collection

6ind propert using Data6indings.Add "ethod passing in propert na"e* data source

to bind to and "e"ber of data source to bind to

0e8t"o85.D%t%"indings.2dd(0e8t+/D%t%Set5.C&stomers/ C&stomerD+);

? 7f binding to source #ithout "ultiple data "e"bers* e.g. collection or arra*

set third par" to blan5 %89&



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Data Currency

? Ever data source "anages navigation using a /urrencanager ob2ect

Data source = 3 or ( D store %DataTable* DataBie#* arra* collection&

Data)et contains "an DataTables* thus "an data sources

/urrencanager 5eeps trac5 of current record for its particular data source

For" "a have "ultiple /urrencanagers associated #ithin its data sources*"anages these through the 6inding/onte4t

/an use 6inding/onte4t to "anage position of current record for each data source

t*is."indingConte8tD%t%Set5.C&stomersE.Position =$;

t*id.bindingConte8tD%t%Set5.C&stomersE.PositionFF;

? .Net #ill not per"it Position propert to be set out of range

/hange of Position propert causes Position/hanged event to be fired ! use to

provide additional processing on "ove %e.g. to indicate #hen range li"it reached&

Comp!e' Binding

? )o"e controls %e.g. +ist6o4* /o"bo6o4* DataCrid& can be bound to "ore

than one record si"ultaneousl

;suall used to displa choices

/reate b setting Data)ource propert* either at design ti"e or via code

)o"e controls* such as +ist6o4 and /o"bo6o4* "ust be bound to single colu"n ! do

this b setting Displae"ber propert

Combo"o85.D%t%So&rce = D%t%Set5.C&stomers;Combo"o85.Dis1l%yMember = C&stomerD+;

i!tering and Sorting

? DataBie# per"its #or5ing #ith subset of data held #ithin DataTable

DataBie# provides "ethods for sorting and filtering data

DataBie# can update DataTable it represents

? /reate DataBie# ! can provide DataTable at construction* or later via Table

propert

D%t%4iew myD%t%4iew = new D%t%4iew(myD%t%0%ble);

Or

D%t%4iew myD%t%4iew = new D%t%4iew();myD%t%4iew.0%ble = myD%t%0%ble;

? /an create at design ti"e. Drag DataBie# fro" Data tab of Toolbo4 to

designer and set its Table propert in the properties #indo#



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6ind controls to DataBie# b setting the Data6indings properties in the Properties

#indo#

)orting acco"plished b setting )ort propert to appropriate colu"n na"e %or

"ultiple colu"ns separated b 8*9&. To sort descending append DE)/ to na"e

myD%t%4iew.Sort = C&stomerD+;myOt*er4iew.Sort = St%te/ City+;myDesc4iew.Sort = St%te D!SC/ City+;

? Filter data through 'o#Filter propert that ta5es string e4pression to be

evaluated #hen selecting records. 6uild co"ple4 e4pressions using AND* O'

and NOT together #ith arith"etic* concatenation and relational operations. 7N

and +7E operators per"it searches for specific strings.

myD%t%4iew.7ow?ilter = City = VSe%ttleI+;

myD%t%4iew.7ow?ilter = City = VDes MoinesI 2D (O0St%te =I2I)+;

myD%t%4iew.7ow?ilter = Price A5.$WX = 6$$+;

myD%t%4iew.7ow?ilter = City (VSe%ttleI/ V0%com%I/V"l%ineI);

myD%t%4iew.7ow?ilter = City ! VSeAtYeI+;

? Additional filtering provided b 'o#)tate propert that can ta5e 3 %or "ore&

of the follo#ing valueso ;nchanged ! displas ro#s that have not been changed

Added ! displas ro#s that have been added

Deleted ! displas ro#s that have been deleted

Origianl'o#s ! original ro#s including unchanged and deleted ro#s

/urrent'o#s ! current ro#s %including added* "odified and unchanged&

odified/urrent ! odified version of original data

odifiedOrigianl ! Original version

? DataBie# has properties that deter"ine if underling data can be edited. 6

default full editable* den access b setting appropriate propert to falseo Allo#Delete ! is deletion of ro#s in underling DataTable allo#ed

Allo#Edit ! is editing of ro#s in underling DataTable allo#ed

Allo#Ne# ! can ro#s be added to underling DataTable

? DataBie#anager is to Data)et #hat DataBie# is to DataTable.

DataBie#anager associated #ith Data)et and "anages DataBie# ob2ects for tables

contained #ithin Data)et

D%t%4iewM%n%ger myM%n%ger = newD%t%4iewM%n%ger(myD%t%Set);



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D%t%4iewM%n%ger myOt*erM%n%ger = newD%t%4iewM%n%ger();

myOt*erM%n%ger.D%t%Set = myOt*erD%t%Set;

? anage 'o#Filter* )ort* etc. through DataBie#)ettings collection

@@ Set 7ow?ilter 1ro1erty of D%t%4iew %ssoci%ted@@ wit* C&stomers t%blemyD%t%4iewM%n%ger.D%t%4iewSettingsC&stomers+E

.7ow?ilter = St%te = V92I+;

? /an retievde DataBie#s via /reateDataBie# "ethod ! re$uires reference to

DataTable

D%t%4iew myD%t%4iew;

myD%t%4iew =myD%t%4iewM%n%ger.Cre%teD%t%4iew(D%t%Set5.0%bles$E)

;

Lesson 5

Retrieving (m!Reader )rom S*!Command

? -"l'eader analogous to Data'eader class ! read onl* for#ard onl access to

-+ returned b $uer

-"l'eader %li5e Data'eader& re$uires e4clusive use of connection

)$l/o""and provides E4ecute-"l'eader "ethod to retrieve -+'eader ob2ect that

e4posed data fro" )$l/o""and as -+ ro#s

),+ $uer e4ecuted b )$l/o""and "ust contain FO' -+ clause

Al#as close -"l'eader to free /onnection

System.Zml.Zml7e%der my7e%der;S,lComm%nd mySKComm%nd = new S,lComm%nd(S!!C0 A

?7OM C&stomers ?O7 ZM 2T0O/ ZMD202+/S,lConnection5);

S,lConnection5.O1en();my7e%der = mySKComm%nd.!8ec&teZml7e%der();

w*ile(my7e%der.7e%d()):

@@ 9rite content %nd m%rN&1 of node %nd its@@ c*ildren

Console.9riteine(my7e%der.7e%dO&terZml());

my7e%der.Close();



21/22

S,lConnection5.Close();

Reading (+, into DataSet

? ;se Data)et.'ead-"l to specif -+ file* strea"* -"l'eader or Te4t'eader

;se Data)et.'ead-"l)che"a to create Data)et #ith specified structure but no data

-riting (+, )rom DataSet

? ;se Data)et.


22/22

System.O.Stre%m9riter(myfile.t8t+);my0r%nsform.0r%nsform(myDoc&ment/ n&ll/ my9riter);
