accessing database programmaticaly in ado.net

8/10/2019 Accessing Database Programmaticaly In ADO.NET

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Programmatic DatabaseAccess with ADO.NET
http://www.apextgi.in/DotNet/AboutDotNet.aspx


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Introducing CS using .NET

J# in Visual Studio .NET

Part 1

Architecture of ADO.NET&


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(e!atio"a! tech"o!og)

ADO.NET is desig"ed to access re!atio"a! databases

E*am!e+

Sales database with customers, orders, and products


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Architecture

ADO.NET architecture based o" data providers data providers encapsulate DB-specific details

Data Provider

ADO.!"

.!" Pro#rammer

DB


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E*isti"g data roviders

.NET curre"t!) shis with ' data roviders+ one for $icrosoft S%& Server

one for Oracle

one for older O&!DB technolo#' (used for ADO, )B*+

one for older ODB (Open Database onnectivit'+ technolo#'

ore third-art) roviders are avai!ab!e&

Oracles own provider http//otn.oracle.com/tech/windows/odpnet/

DB0 http//www1b.software.ibm.com/dmdd/downloads/dotnetbeta/ $'S%& http//www.m's2l.com/, http//crlab.com/m's2lnet/

etc.


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ADO.NET object mode!

ADO.NET is a" object-orie"ted aroach 0!asses are sread across a "umber of 0 "amesaces

some are provider-neutral, others are provider-specific

S%& Server

System.Data.Common

System.Data

System.Data.SqlClient

System.Data.OleDbother DBs, e.#. $S Access

provider-neutral

ODB (Open Database onnectivit'+

System.Data.Odbc


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Part 2

Basic database access&


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Overview of database access

Three stes+

3. open connection to database

0. e4ecute S%& to retrieve records / update DB

5. close connection


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import System.Data.*;

import System.Data.OleDb.*;

String sConnection;sConnection = "Provider=Microsoft.et.O!D#.$.%;" &

"Data So'rce=Sales.mdb";

OleDbConnection dbConn;

dbConn = ne( OleDbConnection)sConnection;dbConn.Open);

Message#o+.S,o()dbConn.get-State).toString);

import System.Data.*;

import System.Data.OleDb.*;

String sConnection;sConnection = "Provider=Microsoft.et.O!D#.$.%;" &

"Data So'rce=Sales.mdb";


dbConn = ne( OleDbConnection)sConnection;dbConn.Open);

Message#o+.S,o()dbConn.get-State).toString);

617 Oe" co""ectio"

0o""ectio"s are oe"ed based o" connection stringi"fo

here we open a connection to a $S Access 0666 database

7Sales.mdb7 must e4ist in same dir as .!8! (e.#. bin9Debu#+

connection


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Bui!di"g co""ectio" stri"gs

0o""ectio" stri"gs are ve"dor-secific

0o""ectio" stri"gs are "ot we!!-docume"ted

8here to tur" for he!9

www.connectionstrin#s.com

www.able-consultin#.com/ADO:conn.htm
http://www.connectionstrings.com/http://www.able-consulting.com/ADO_conn.htmhttp://www.able-consulting.com/ADO_conn.htmhttp://www.connectionstrings.com/


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627 (etrieve records

(etrieve records via $: $e!ect ;uer)

read-onl' access viaDataReader; field names

String sql fn ln; C'stomer c;sql = "Select * /rom C'stomers Order #y !ast0ame 1sc /irst0ame 1sc;";

OleDbCommand dbCmd;OleDbData2eader db2eader;

dbCmd = ne( OleDbCommand)sql dbConn;db2eader = dbCmd.+ec'te2eader);

(,ile ) db2eader.2ead) // retrieve records one-by-one

3 fn = String.val'eOf)db2eader.get-4tem)"/irst0ame"; ln = String.val'eOf)db2eader.get-4tem)"!ast0ame"; c = ne( C'stomer)fn ln; t,is.list#o+5.get-4tems).1dd)c;

6

String sql fn ln; C'stomer c;sql = "Select * /rom C'stomers Order #y !ast0ame 1sc /irst0ame 1sc;";

OleDbCommand dbCmd;OleDbData2eader db2eader;

dbCmd = ne( OleDbCommand)sql dbConn;db2eader = dbCmd.+ec'te2eader);

(,ile ) db2eader.2ead) // retrieve records one-by-one

3 fn = String.val'eOf)db2eader.get-4tem)"/irst0ame"; ln = String.val'eOf)db2eader.get-4tem)"!ast0ame"; c = ne( C'stomer)fn ln; t,is.list#o+5.get-4tems).1dd)c;

6

data readerrecord

recordrecord

field name of data value in current record

command connection


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6%7 0!ose co""ectio"

Be sure to c!ose reader a"d co""ectio"&

to flush pendin# updates (in #eneral+

so others can access DB (connections are limited resources+

db2eader.Close);

dbConn.Close);

db2eader.Close);

dbConn.Close);


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Part %

Data-drive" a!icatio" desig"&


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Data Tier desig"

(eca!! N-Tier desig"&


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DB c!osed via try-catch-finallyatter"

and


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Part '

#dati"g a database&


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Basic idea

Oe"? e*ecute? a"d c!ose+

String sConnection sql;sConnection = "...";

sql = "...";


OleDbCommand dbCmd;dbConn = ne( OleDbConnection)sConnection;dbCmd = ne( OleDbCommand)sql dbConn;

int ro(s;

dbConn.Open);

ro(s = dbCmd.+ec'te0on


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D)"amic $:

ost of the time )ou@!! "eed to bui!d $: d)"amica!!)

i.e. based on input values from the user

E*am!e+

delete the selected customer?

String fn ln;

C'stomer c;

c = t,is.list#o+5.get-Selected4tem);

fn = c.first0ame;ln = c.last0ame;

sql = "...";

String fn ln;

C'stomer c;

c = t,is.list#o+5.get-Selected4tem);

fn = c.first0ame;ln = c.last0ame;

sql = "...";


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D)"amic stri"g bui!di"g

D)"amic $: re;uires d)"amic stri"g bui!di"g

E*am!e+

build d'namic S%& to delete selected customer?

dont for#et the delimiters for strin#s ; dates@

String sql;

sql = String./ormat)"Delete /rom C'stomers 9,ere " & "/irst0ame=>3%6> 1nd !ast0ame=>356>;"

fn ln;

String sql;

sql = String./ormat)"Delete /rom C'stomers 9,ere " & "/irst0ame=>3%6> 1nd !ast0ame=>356>;"

fn ln;


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E*am!e

De!ete se!ected customer&

private void list#o+5-Selected4nde+C,anged)83 String fn ln sql; int ro(s; C'stomer c; c = )C'stomer t,is.list#o+5.get-Selected4tem); if )c == n'll ret'rn; // nothing selected

fn = c.first0ame; ln = c.last0ame; sql = String./ormat)"Delete /rom C'stomers 9,ere " & "/irst0ame=>3%6> 1nd !ast0ame=>356>;" fn ln; . . . dbConn.Open); ro(s = dbCmd.+ec'te0on3%6> 1nd !ast0ame=>356>;" fn ln; . . . dbConn.Open); ro(s = dbCmd.+ec'te0on


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Oos

Tr) to de!ete O@Dah!? Cathie&

8hat hae"s9


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Escai"g de!imiters

ost commo" DB rogrammi"g mistae+

for#ettin# to escape delimiter characters?

$o!utio"9

=ust replace with 0 in a row, i.e.


fn = c.first0ame;

ln = c.last0ame;

fn = fn.2eplace)">" ">>"; ln = ln.2eplace)">" ">>"; sql = String./ormat)"Delete /rom C'stomers 9,ere " & "/irst0ame=>3%6> 1nd !ast0ame=>356>;" fn ln;


fn = c.first0ame;

ln = c.last0ame;

fn = fn.2eplace)">" ">>"; ln = ln.2eplace)">" ">>"; sql = String./ormat)"Delete /rom C'stomers 9,ere " & "/irst0ame=>3%6> 1nd !ast0ame=>356>;" fn ln;


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Data$ets

Data$ets are a" i"-memor) data structure

easil' filled with data from a database

easil' passed around

easil' displa'ed in a C app

Data$et

Name Price $toc

Ants 6.EF G666

Birds E.EF G66

ats 0F.FG 366

Do#s 1F.FG 06

DBommand onnectionDataAdapter

Data$et mirrors the database

data forms a temporar' table called7"able7 within DataSet

Tab!e


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i!!i"g a Data$et

DataAdater object is used to fi!! a Data$et&

E*am!e+

fill DataSet with all product data

sql = "Select * /rom Prod'cts Order #y 0ame 1sc;";

...

DataSet ds;

OleDbData1dapter adapter;

ds = ne( DataSet);

adapter = ne( OleDbData1dapter)dbCmd;

dbConn.Open);

adapter./ill)ds;

dbConn.Close);

sql = "Select * /rom Prod'cts Order #y 0ame 1sc;";

...

DataSet ds;

OleDbData1dapter adapter;

ds = ne( DataSet);

adapter = ne( OleDbData1dapter)dbCmd;

dbConn.Open);

adapter./ill)ds;

dbConn.Close);

Tab!e

Name Price $toc

Ants 6.EF G666

Birds E.EF G66

ats 0F.FG 366

Do#s 1F.FG 06


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Data


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Data


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!ushi"g cha"ges bac to database

(eco""ect? a"d a!) adater@s %pdate'(method

use )ommand*uilderob=ect to #enerate necessar' S%& for 'ou

// retrieve existing data set from gridds = )DataSet t,is.data?rid5.get-DataSo'rce);

...

OleDbCommand#'ilder cmd#'ilder;cmd#'ilder = ne( OleDbCommand#'ilder)adapter;

dbConn.Open);

adapter.Apdate)ds; // this ill thro exception if update's( conflictdbConn.Close);

// retrieve existing data set from gridds = )DataSet t,is.data?rid5.get-DataSo'rce);

...

OleDbCommand#'ilder cmd#'ilder;cmd#'ilder = ne( OleDbCommand#'ilder)adapter;

dbConn.Open);

adapter.Apdate)ds; // this ill thro exception if update's( conflictdbConn.Close);


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$ummar)

Databases are a critica! como"e"t of most busi"ess as

$: is the sta"dard rogrammi"g !a"guage for databases

Database rogrammi"g is based o" framewor c!asses

in .!", those classes are called ADO.!"

the more 'ou Hnow about S%& the better


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accessing database programmaticaly in ado.net

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