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 JDBC•

 #$e JDBC % Java Data&ase Connectivit'(

• An AP t$at de)nes interfaces and classes forwriting data&ase applications in Java &'

ma*ing data&ase connections"

• +or*s wit$ almost an' relational data&ase"

•  JDBC is a Java AP for e,ecuting S-.statements and supports &asic S-.functionalit'"

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 JDBC Arc$itecture

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 JDBC Basics

• import java.sql.*;

• Steps/" .oading a data&ase driver

0" Creating a 1d&c Connection

3" Creating a 1d&c Statement o&1ect2" ,ecuting a S-. statement wit$ t$e Statemento&1ect4 and returning a 1d&c resultSet

5" ,tract data from result set

6" Cleanup environment

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Data&ase driver stringSamples

• m'S-. 7 com"m's8l"1d&c"Driver

•S8lserver 7com"microsoft"1d&c"s8lserver"S-.ServerDriver

• Apac$e Der&' 7 org"apac$e"der&'"1d&c"ClientDriver

• MSAccess %30 &it( 7 sun"1d&c"od&c"Jd&cOd&cDriver

• MSAccess %62 &it( 7Provider7Microsoft"AC"O.DB"/0"9 $ttp!::www"microsoft"com:downloads:details"asp,;

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DB Connection .Samples

eneral format!

1d&c!s8lserver!::server!portData&aseEame7d&name

• mysql = jdbc:mysql://localhost/dbname

• Sql server = jdbc:microsot:sqlserver://localhost:!"##;databa

se$ame=dbname• ms access = jdbc:odbc:%mp

• Derby = jdbc:derby://localhost:!&'(/DBname

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!. )oadin a database driver

tr' G

Class"forEame%HDB driver string pat$I(

Catc$%,ception e(

G

S'stem"out"println%Huna&le to load t$e

driverI(

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'. Creatin a jdbc Connection

try+

Connection dbCon = n,ll;

dbCon = Driver-anaer.etConnectionDB

conneciton 01) 2,ser2p34

5

catch S6)%7ception 7 4+

System.o,t.println Co,ldn8t et connection9 4;5

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3" Creating a 1d&c Statement o&1ect

Statement stmt = dbCon.createStatement4;

2" ,ecuting a S-. statement

String s 7 KS.C# id4 )rst4 last4 age

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&. %7tract data rom res,lt set

w$ile%rs"ne,t%( ( G

 ::etrieve &' column name

S'stem"out"print%Hid 7I Lrs"getnt%KidK( (

S'stem"out"print%Hage 7 H L rs"getnt%KageK( (  S'stem"out"print%Hfname 7 H Lrs"getString%K)rstK( (

S'stem"out"print%Hl name 7 H L

rs"getString%KlastK( (

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S#P 6! Cleanup environmentrs"close%( :: close result set

stmt"close%( :: close d& statement

d&Con"close%( :: close d& connection

catc$%S-.,ception se( ::andle errors for JDBC

G se"printStac*#race%(

 

catc$%,ception e( ::andle errors for Class"forEame

G e"printStac*#race%(

 

)nall'G ::)nall' &loc* used to close resources

if%stmtN7null(  stmt"close%(

if%d&ConN7null(

  conn"close%(

:: end )nall'

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Complete Code Structuretry+

static nal Strin DBDriver = DB Driver strin;

static nal Strin DBCon = DB connection strin;

Strin sql6,ery = 1?- %mployees

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 JDBC Statement #'pes

• Statement

•

@repared Statement

• Callable Statement

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Statement: 

,ecute simple s8l 8ueries wit$out parameters"S'nta, ! Statement createStatement%(

@repared Statement: ,ecute precompiled s8l 8ueries wit$ or wit$outparameters"S'nta, ! PreparedStatementprepareStatement%String s8l(

Callable Statement: ,ecute a call to a data&ase stored procedure"

S'nta, ! Calla&leStatement prepareCall%String s8l(

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Statement• se for generalpurpose access to 'our data&ase"

•

,ecute simple s8l 8ueries wit$out parameters"• 'ou can t$en use it to e,ecute a S-. statement wit$ one of

its t$ree e,ecute met$ods"

• Synta7 : – stmt 7 conn"createStatement% ( – stmt"close%(

• 'ou can t$en use it to e,ecute a S-. statement wit$ one of its t$reee,ecute met$ods"

• boolean e7ec,teStrin S6)4 !

 – se t$is met$od to e,ecute S-. DD. statements or w$en 'ou needto use trul' d'namic S-."

• int e7ec,te0pdateStrin S6)4 : – se t$is met$od to e,ecute S-. statements for w$ic$ 'ou e,pect

to get a num&er of rows aected for e,ample4 an ES#4PDA#4 or D.# statement"

• 1es,ltSet e7ec,te6,eryStrin S6)4 :

 – eturns a esultSet o&1ect" se t$is met$od w$en 'ou e,pect toget a result set4 as 'ou would wit$ a S.C# statement"

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esult Sets Details

• A esultSet is a ta&ular structurecontaining t$e dataset returned &'e,ecuting a 8uer' statement"

• t contains &ot$ t$e data itself andmetadata"

• A esultSet o&1ect is readonl' andforwardonl' &' default"

 

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esult Set cont""

•  #$e esultSet o&1ect provides t$e necessar'met$ods to! – iterate over t$e rows &ot$ forward and &ac*ward"

 –

read or update eac$ column content" – insert new rows into t$e esultSet and )nall' into

t$e underl'ing ta&le"

 – delete rows from t$e esultSet and t$eunderl'ing ta&le"

 – ead t$e metadata associated wit$ t$e esultSet

 – 1ump &etween rows &' providing t$e a&solute rownum&er"

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esultSet ow #o;

1es,ltSet-etaData rsmd = n,ll;

• Ao3 to et total col,mns ret,rned in a1es,ltSet  – rsmd"getColumnCount%(

• Ao3 to et col,mn names or ro3s ret,rned ina 1es,ltSet

 – rsmd 7 rs"getMetaData%( – String value 7 rsmd"getColumnEame%/(

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esultSet ow #o;•

Ao3 do create an ,pdatable1es,ltSetSome conditions appl' to t$e updata&leesultSet! –

 #$e S.C# statement must $ave a single underl'ing ta&leno 1oins and no aggregation functions are allowed"

 –  #$e P of t$e underl'ing ta&le must &e present in t$eesultSet so it can propagate t$e c$anges to t$e correctrow in t$e ta&le"

Statement stmt 7connection"createStatement% esultSet"#QPRSCO..RSES#V4esultSet"COECRPDA#AB.(

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esultSet ow #o;

• Ao3 can ,pdate a 1es,ltSetprorammatically

Statement stmt 7

conn"createStatement%esultSet"#QPRSCO..RSES#V4 esultSet"COECRPDA#AB.(

esultSet rs 7 stmt"e,ecute-uer'%KS.C# name

4lastEame 4sn

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Create StatementArguments

•  #$e )rst argument in CreateStatement indicates t$e t'pe oft$e esultSet o&1ect ! – E@%F>?1GH1DF?$)E: #$e esultSet will onl' allow t$e cursor to go forward"

 – E@%F SC1?))F$S%$SI%: #$e cursor can scroll forwards and&ac*wards4 and t$e result set is not sensitive to c$anges made &' ot$ers

to t$e data&ase t$at occur after t$e result set was created" – E@%FSC1?))FS%$SI%: #$e cursor can scroll forwards and

&ac*wards4 and t$e result set is sensitive to c$anges made &' ot$ers tot$e data&ase t$at occur after t$e result set was created"

•  #$e second argument in CreateStatement indicates w$et$er

t$e esultSet is updata&le or not" #$e following values areaccepta&le for t$is parameter! – C?$C01F1%HDF?$)E: A esultSet of t$is t'pe is readonl'

 – C?$C01F0@DHHB)% : +e can update t$e resultset created wit$ t$is valuefor t$e mentioned parameter"

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• +e can iterate forward in t$is esultSetusing t$e following snippet

w$ile %rs"ne,t%(( G

  String name 7 rs"getString%KnameK(

  String lastEame 7 rs"getString %KlastEameK(  String sn 7 rs"getString%HsnI(

  S'stem"out"println%name L K K L lastEame L H I Lsn(

• se rs"previous%( instead of rs"ne,t toiterate &ac*word"

• Delete a speci)c row – rset"a&solute%5(

 – rset"deleteow%(

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•  #o e,ecute a 8uer' to update a ta&leor delete some row in t$e ta&le use

esultset"e,ecuteupdate%( function"