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BLOBs and CLOBs: Storing large fields in a table with the other datais not necessarily the optimum place especially if the data has a

variable size. One way to handle large, variable sized objects is withthe Large Objects (LOs! type. LOs use a locator, essentially a

pointer, in the database record that points to the real database field.

"here are two types of LOs: inary Large Objects (LOs! and#haracter Large Objects (#LOs!. $hen you access a LO or #LO,

the data is not copied to the client. "o retrieve the actual data from a

result set, you have to retrieve the pointer with a call to BLOB

blob=getBlob(1)or CLOB clob=getClob(1), and then retrieve the data with

a call to blob.getBinaryStream()or clob.getBinaryStream().

y default, % statements are processed in full auto'commit mode.

Storing Classes, Images and Other Large Objects

any databases can store binary data as part of a row if the database

field is assigned a long raw, longvarbinary, or other similar type. "hese

fields can accommodate up to two )igabytes of data. "his means if

you can convert the data into a binary stream or array of bytes, it canbe stored and retrieved from the database in the same way you would

store a string or double.

"his techni*ue can be used to store and retrieve images and %ava

objects.

Storing and retrieving an image: +t is very easy to store an object

that can be serialized or converted to a byte array. nfortunately,

java.awt.Imageis not Serializable. -owever, as shown in this net code

eample, you can store the image data to a file and store the theinformation in the file as bytes in a database binary field.

int itemnumber=44!"#

$ile %ile = new $ile(itemnumber&'.jg')#

$ileInutStream %i = new $ileInutStream(%ile)# *reare+Statement tmt = con.reareStatement('u+ate auctionitemet t,eimage=- w,ere i+= -')#

tmt.etBinaryStream(1 %i (int)%ile.lengt,())/ tmt.etInt(0 itemnumber)# tmt.eecute2+ate()# tmt.cloe()# %i.cloe()#

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"o retrieve this image and create a byte array that can be passed to

createImage, do the following:int itemnumber=44!"#

byte3 imageByte#*reare+Statement tmt = con.reareStatement(

'elect t,eimage %rom auctionitem w,ere i+= -')# tmt.etInt(1 itemnumber)# 5eultSet r=tmt.eecute6uery()# i%(r.net()) 7 imageByte = r.getByte(1)# 8 tmt.cloe()# r.cloe()#

Image auctionimage =9ool:it.get;e%ault9ool:it().createImage( imageByte)#

Storing and retrieving an object: / class can be serialized to abinary database field in much the same way as the image was in theprevious eample. +n this eample, the 5egitrationImlclass is

changed to support default serialization by adding imlement

Serializableto the #lass declaration.

0et, a Byte

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reg.balance = balance#

Bytecetion ignore) 7 8 8 8

"he object is retrieved and reconstructed by etracting the bytes fromthe database, creating a Byte

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i% (: == null) 7 t,row new $in+er>cetion ()# 8 Connection con = null# *reare+Statement = null# try 7 con=getConnection()# =con.reareStatement('

elect t,ecla %romregitration w,ere t,euer = -')#

.etString(1 :.t,euer())# .eecute6uery()# 5eultSet r = .get5eultSet()# i%(r.net())7 byte3 regByte = r.getByte(1)# Bytecetion ignore) 78 8 8

BLOBs and CLOBs: Storing large fields in a table with the other datais not necessarily the optimum place especially if the data has a

variable size. One way to handle large, variable sized objects is with

the Large Objects (LOs! type. LOs use a locator, essentially apointer, in the database record that points to the real database field.

"here are two types of LOs: inary Large Objects (LOs! and#haracter Large Objects (#LOs!. $hen you access a LO or #LO,

the data is not copied to the client. "o retrieve the actual data from a

result set, you have to retrieve the pointer with a call to BLOB

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blob=getBlob(1)or CLOB clob=getClob(1), and then retrieve the data with

a call to blob.getBinaryStream()or clob.getBinaryStream().

Controlling Transactions

y default, % statements are processed in full auto'commit mode."his mode wor1s well for a single database *uery, but if an operation

depends on several database statements that all have to completesuccessfully or the entire operation is cancelled, a finer transaction is

needed.

/ description of transaction isolation levels is covered in more detail in#hapter 2: &ata and "ransaction anagement. "o use transaction

management in the % platform, you first need to disable the full

auto'commit mode by calling:

Connection con= getConnection()# con.et

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8 Calen+ar currenttime=Calen+ar.getIntance()# java.util.;ate current+ate=currenttime.get9ime()# tart+ate=new java.@l.;ate( current+ate.get9ime())# currenttime.a++(Calen+ar.; auction+ay)# en++ate=new java.@l.;ate((

currenttime.get9ime()).get9ime())#

=con.reareStatement( 'inert into auctionitem(

i+ +ecrition tart+ate en++atetartrice ummary)value (------)')#

.etInt(1 count)# .etString(0 +ecrition)# .et;ate(A tart+ate)# .et;ate(4 en++ate)# .et;ouble(! tartrice)# .etString(" ummary)#

.eecute2+ate()# .cloe()#

=con.reareStatement('u+ate regitrationet balance=balance .!w,ere t,euer= -')#

.etString(1 eller)# .cloe()# tmt= con.createStatement()# tmt.eecute6uery(

'elect balance %rom regitrationw,ere t,euer='&eller&'')#

r = tmt.get5eultSet()# i%(r.net()) 7 balance=r.get;ouble(1)# 8 tmt.cloe()# i%(balance D) 7 con.rollbac:()# con.cloe()# return (1)# 8

tmt= con.createStatement()# tmt.eecute2+ate(

'u+ate auctionitem et

counter=counter&1')# tmt.cloe()# con.commit()# con.cloe()# return()# 8 catc,(S6L>cetion e) 7 try 7 con.rollbac:()# con.cloe()# tmt.cloe()#

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.cloe()# 8catc, (>cetion ignore)78 8 return ()# 8

Escaping Characters

"he % /5+ provides the ecae1eyword so you can specify the

character you want to use to escape characters. 6or eample, if you

want to use the percent sign (E! as the percent sign and not have it

interpreted as the S7L wildcard used in S7L LI>*ueries, you have to

escape it with the escape character you specify with the ecae

1eyword.

"his net statements shows how you would use the ecae1eyword to

loo1 for the value 1E.tmt.eecute6uery(

'elect ta %rom ale w,ere ta li:e1FE 7ecae F8')#

+f your program stores names and addresses to the database entered

from the command line or by way of a user interface, the single *uotes(! symbol might appear in the data. 5assing single *uotes directly into

a S7L string causes problems when the S7L statement is parsedbecause S7L gives this symbol another meaning unless it is escaped.

"o solve this problem, the following method escapes any symbol

found in the input line. "his method can be etended to escape any

other characters such as commas that the database or database

driver might interpret another way.

tatic ublic String ecaeLine(String ) 7 String retvalue = # i% (.in+eO% ('') ?= 1 ) 7 StringBu%%er ,ol+ = new StringBu%%er()# c,ar c# %or(int i=# i D .lengt,()# i&& ) 7 i% ((c=.c,ar

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-owever, if you use a *reare+Statementinstead of a simple Statement,

most of these escape problems go away. 6or eample, instead of this

line with the escape se*uence:tmt.eecute6uery('elect ta %rom ale w,ere ta li:e

1FE 7ecae F8')#

8ou could use this line:reare+tmt = C.reareStatement( 'u+ate ta et ta = -')#

Mapping Database Types

/part from a few % types such as IG9>H>5that are represented as

an IG9>H>5in most popular databases, you might find that the %

type for a table column does not match the type as it is represented inthe database. "his means calls to 5eultSet.getObject,

*reare+Statement.etObjectand CallableStatement.getObject()will veryli1ely fail.

8our program can determine the database column type from thedatabase meta data and use that information to chec1 the value before

retrieving it. "his net code chec1s that the value is in fact type

IG9>H>5before retrieving its value.

int count=# Connection con=getConnection()# Statement tmt= con.createStatement()# tmt.eecute6uery(

'elect counter %rom auctionitem')# 5eultSet r = tmt.get5eultSet()# i%(r.net()) 7 i%(r.geteta;ata().getColumn9ye(1) ==

9ye.IG9>H>5) 7 Integer i=(Integer)r.getObject(1)# count=i.intJalue()# 8 8 r.cloe()#

Mapping Date types

"he ;type is where most mismatches occur. "his is because the

java.util.;ateclass represents both &ate and "ime, but S7L has the

following three types to represent data and time information:

/ ;type that represents the date only (92;2 / 9I>type that specifies the time only (=;:92:>

/ 9I>S9

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"hese three additional types are provided in the java.@lpac1age as

java.@l.;ate, java.@l.9imeand java.@l.9imetamand are all

subclasses of java.util.;ate. "his means you can use convert

java.util.;atevalues to the type you need to be compatible with the

database type.

ote!"he 9imetamclass loses precision when it is

converted to a java.util.;atebecause java.util.;atedoes

not contain a nanosecond field, it is better to not convert a

9imetaminstance if the value will be written bac1 to the

database.

"his eample uses the java.@l.;ateclass to convert the java.util.;ate

value returned by the call to Calen+ar.get9imeto a java.@l.;ate.

Calen+ar currenttime=Calen+ar.getIntance()# java.@l.;ate tart+ate= new java.@l.;ate(( currenttime.get9ime()).get9ime())#

8ou can also use the java.tet.Simle;ate$ormatclass to do the

conversion. "his eample uses the java.tet.Simle;ate$ormatclass to

convert a java.util.;ateobject to a java.@l.;ateobject:

Simle;ate$ormat temlate =new Simle;ate$ormat('yyyy++')#

java.util.;ate en++ate =new java.util.;ate('1KA1K')#

java.@l.;ate @l;ate =java.@l.;ate.valueO%( temlate.%ormat(en++ate))#

+f you find a database date representation cannot be mapped to a %ava

type with a call to getObjector get;ate, retrieve the value with a call to

getStringand format the string as a ;atevalue using the

Simle;ate$ormatclass shown above.

What is JServer and what is it used for?

Oracle JServer Option is a Java Virtual Machine (Java VM) which runs within the Oracle database server'saddress space. Oracle also provides a JServer Accelerator to compile Java code natively. This speeds up theeecution o! Java code by eliminatin" interpreter overhead.

#ac$ to top o! !ile

http://www.orafaq.com/faqjdbc.htm#TopOfFilehttp://www.orafaq.com/faqjdbc.htm#TopOfFile

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How does one install the Oracle JServer Option?

%ollow these steps to activate the Oracle JServer& JVM option

Ma$e sure your database is started with lar"e avapoolsi*e (+,-M) and sharedpoolsi*e

(+-M) /0/T.O1A parameter values.

1un the 2O1A3456OM5&avavm&install&initvm.s7l script !rom S8S AS S8S9#A to install the

Oracle JServer Option on a database.

:rant JAVA;S514 statements or 4 code. 4oo$ at this eample

create or relace %unction ,ello (tr varc,ar0) return varc,ara language java name ello.g(java.lang.String) returnjava.lang.String# K

#ac$ to top o! !ile

What is JDBC and what is it used for?

J9#3 is a set o! classes and inter!aces written in Java to allow other Java pro"rams to send S>4 statementsto a relational database mana"ement system.

Oracle provides three cate"ories o! J9#3 drivers

http://www.orafaq.com/faqjdbc.htm#TopOfFilehttp://www.orafaq.com/scripts/plsql/java.txthttp://www.orafaq.com/scripts/plsql/java.txthttp://www.orafaq.com/faqjdbc.htm#TopOfFilehttp://www.orafaq.com/faqjdbc.htm#TopOfFilehttp://www.orafaq.com/faqjdbc.htm#TopOfFilehttp://www.orafaq.com/scripts/plsql/java.txthttp://www.orafaq.com/faqjdbc.htm#TopOfFilehttp://www.orafaq.com/faqjdbc.htm#TopOfFile

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J9#3 Thin 9river (0o local 0et? installation re7uired& handy !or applets)

J9#3 O3/ !or writin" stand@alone Java applications

J9#3 5SIOG')# w,ile (ret.net())

http://www.orafaq.com/faqjdbc.htm#TopOfFilehttp://www.orafaq.com/faqjdbc.htm#TopOfFile

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Sytem.out.rintln (ret.getString(1))# KK *rint col 1 tmt.cloe()# 88

#ac$ to top o! !ile

How does one connect with the JDBC OC Driver?

One must have 0et? (S>4B0et) installed and wor$in" be!ore attemptin" to use one o! the O3/ drivers.imort java.@l.P#cla +bcetion 7 try 7 Cla.%orGame ('oracle.j+bc.+river.Oracle;river')# 8 catc, (ClaGot$oun+>cetion e) 7 e.rintStac:9race()# 8

Connection conn = ;riveranager.getConnection ('j+bc/oracle/ociU/Q@itu@cbiworcl' 'cott' 'tiger')# KK or ociV Q9GSGame>ntry ueri+ awor+

Statement tmt = conn.createStatement()# 5eultSet ret = tmt.eecute6uery('elect B5 %romSRS.JTJ>5SIOG')# w,ile (ret.net()) Sytem.out.rintln (ret.getString(1))# KK *rint col 1 tmt.cloe()# 88

#ac$ to top o! !ile

How does one connect with the JDBC !"#B Driver?

One can obtain a handle to the de!ault or current connection (

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8

#ac$ to top o! !ile

Where can one $et %ore info about JDBC?

9ownload Sun's Java 9evelopers it and various other A4 access in Java. /t provides a Java precompiler that translatesS>4J call to J9#3 calls. The idea is similar to that o! other Oracle 4J is more concise and thus easier to write than J9#3E and provides compile@time schema validationand synta chec$in" !or easier debu""in". S>4J reads input either !rom a B.S>4J !ileE or a Java source !ilein which S>4J statements are embedded. The S>4J precompiler translates the S>4J statements into theire7uivalent J9#3 calls. S>4J supports static S>4.

#ac$ to top o! !ile

How does one write S&J pro$ra%s?

See the Scripts and sample pro"ramssection !or some S>4J eample pro"rams. #ac$ to top o! !ile

How does one deploy S&J pro$ra%s?

;se the s7l compiler to compile your B.s7l !iles to B.ava and B.ser !iles. The B.ser !iles contain vendorspeci!ic database code. Therea!ter one invo$es the avac compiler to compile the .ava !iles to B.class !iles.The B.class and B.ser !iles needs to be deployed. #ac$ to top o! !ile

Where can one $et %ore info about S&J?

The S>4J Or"ani*ation

Sun's /n!o#us 3ontrols

#ac$ to top o! !ile

What is JDeveloper and what is it used for?

http://www.orafaq.com/faqjdbc.htm#TopOfFilehttp://java.sun.com/products/jdbc/http://java.sun.com/docs/books/tutorial/jdbc/basics/gettingstarted.htmlhttp://java.sun.com/docs/books/tutorial/jdbc/basics/gettingstarted.htmlhttp://www.oracle.com/downloadhttp://sunsite.unc.edu/javafaq/javafaq.htmlhttp://www.orafaq.com/faqjdbc.htm#TopOfFilehttp://www.orafaq.com/faqpro.htmhttp://www.orafaq.com/faqjdbc.htm#TopOfFilehttp://www.orafaq.com/faqscrpt.htm#SQLJhttp://www.orafaq.com/faqscrpt.htm#SQLJhttp://www.orafaq.com/faqjdbc.htm#TopOfFilehttp://www.orafaq.com/faqjdbc.htm#TopOfFilehttp://www.sqlj.org/http://www.sqlj.org/http://java.sun.com/beans/infobus/http://www.orafaq.com/faqjdbc.htm#TopOfFilehttp://www.orafaq.com/faqjdbc.htm#TopOfFilehttp://java.sun.com/products/jdbc/http://java.sun.com/docs/books/tutorial/jdbc/basics/gettingstarted.htmlhttp://www.oracle.com/downloadhttp://sunsite.unc.edu/javafaq/javafaq.htmlhttp://www.orafaq.com/faqjdbc.htm#TopOfFilehttp://www.orafaq.com/faqpro.htmhttp://www.orafaq.com/faqjdbc.htm#TopOfFilehttp://www.orafaq.com/faqscrpt.htm#SQLJhttp://www.orafaq.com/faqjdbc.htm#TopOfFilehttp://www.orafaq.com/faqjdbc.htm#TopOfFilehttp://www.sqlj.org/http://java.sun.com/beans/infobus/http://www.orafaq.com/faqjdbc.htm#TopOfFile

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J9eveloper is the Oracle /95 (/nte"rated 9evelopment 5nvironment) !or developin" S>4J and J9#3pro"ramsE appletsE stored proceduresE 5J#'sE JS

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How does a JS" $ets e*ecuted?

The !irst time you call a JS

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How does on drop a Java Stored "rocedure fro% the database?

S>4B4B4J s7l K call ...L e" s7l K call A3M5.#5:/0150TA4(in member/9E in

employee/9E outE ...) LH

import ava.s7l.BH

public class 3reate3o!!ees K public static void main(Strin" ar"sN) K Strin" url =dbcmySubprotocolmy9ataSource=H 3onnection conH Strin" createStrin"H createStrin" =create table 3O%%55S = P =(3O%0AM5 VA136A1(Q,)E = P

=S;

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L catch(S>45ception e) K System.err.println(=S>45ception = P e."etMessa"e())H L L

L