Copyright 2004all rights reserved 1 JAVA & PL/SQL For Oracle RDBMS (8i & 9i) By Joel A. Thompson ([email protected])

copyright 2004 all rights reserved www.rhinosystemsinc.com

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JAVA & PL/SQL

For Oracle RDBMS (8i & 9i)By Joel A. Thompson ([email protected])

www.rhinosystemsinc.com

05/2004


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INTRODUCTION

Joel A. Thompson 15 years of industry experience Consultant: Architecture, Software

Engineering and Project Manager Java and Oracle expert


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OVERVIEW Basics of PLSQL Optimizing RDBMS Calls from JAVA

Return Values & Cursors

Logic processing on Server, ARRAY inserts

And more …

Examples WRAP UP / Q&A


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Getting Started with Java

Must install a JDK & IDE– JDK (Java Developers Kit) from Sun

http://java.sun.com/j2se/1.4/index.html– IDE (Integrated Developers Environment)

• Oracle’s JDeveloper (technet.oracle.com)• IntelliJ: (www.intellij.net)• Textpad: http://www.textpad.com


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Getting Started with Oracle Server Install Oracle (Steps)

– Download/Install from technet.oracle.com– Create the database, use Oracle's Database Configuration

Assistant.– Make sure network listeners are started – typically your

instance will be available on port 1525 – use Oracle's Net Configuration Assistant, to configure a "Listener".

Client Requirement– Copy the $ORACLE_HOME/jdbc/lib/classes12.jar to your

client side's CLASSPATH.– Connect string example (thin driver) – requires no client side

libraries: jdbc:oracle:thin:joel/welcome@localhost:1521:UCDBA


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Client Server Java/PLSQL Architecture


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What is PL/SQL? A programming language

– If/then/else– Loops– Function calls– Transactional– Procedural

Feature rich Performance Gain Oracle only


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Some Good Reasons to use PL/SQL Basically you'd like to do some logic on the server side in one

call to the database Transaction support within the PL/SQL Temporary table queries/inserts to filter data further before

returning result set Take advantage of server side resources while processing you

PL/SQL – send message out through Oracle's Advanced Queuing.

Distributed Computing – update another database… You want to abstract your database layer into Oracle, such

that you can change the table's or columns around without affecting the client program.


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Ways to call PL/SQL

ADHOC– Send the PL/SQL block of code from the client

java program to the server for processing. FUNCTION

– Client Side calls a PL/SQL function in Oracle. PL/SQL is already compiled and loaded in Oracle.

– Function will return a value PROCEDURE

– Client calls a PL/SQL procedure– Similar to function, but does not return values.


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ADHOC: Java Client Example 1

SQL embedded in call from Java Client// EXAMPLE OF SIMPLE SELECT STATEMENT

Statement stmt=connection.createStatement();

// QUERY THE ENTIRE TABLE

String sSQL="select ACCOUNT_ID,SSNO,FNAME,LNAME,PHONE from PERSON order by account_id";

// GET THE RESULT SET AND PROCESS IT.

ResultSet rs=stmt.executeQuery(sSQL);

while(rs.next())

{

nPERSON_ID=rs.getInt(1);

sSSNO=rs.getString(2);

…/// check to see if matches with new account you'd like to add.

}

// IF ACCOUNT DOESN'T ALREADY EXIST, THEN ADD IT HERE:

stmt.executeUpdate("insert into PERSON(ACCOUNT_ID,SSNO,FNAME,LNAME) values(account_id_seq.nextval," +

"'" + sSSNO + "'," + "'" + sFNAME + "'," +"'" + sLNAME + "'");


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Issues Regarding Example 1

Selecting from entire table is generally a bad idea. (unless small "lookup table").

One call for the Query, and 2nd call to create the account.


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ADHOC: Java Client Example 2 Prepared Statement/Bind from Java Client

public void initializeOnce(){ // THE SQL INSERT TO BE MADE.String sQueryNotify="insert into PERSON (PERSON_ID,SSNO,FNAME,LNAME)" + " values (person_id_seq.nextval,?,?,?)";

// CREATE A PREPARED STATEMENT, BASED ON THE ABOVE SQLm_psInsertPerson=conn.prepareStatement(sQueryNotify);}

public void insertNewPerson(String SSNO,String FNAME,String LNAME){ // BIND THE PARAMETER - REUSE THE ALREADY CREATED PREPARED STATEMENT m_psInsertPerson.setString(1, SSNO); m_psInsertPerson.setString(2, FNAME); m_psInsertPerson.setString(3, LNAME);

// EXECUTE THE INSERT m_psInsertPerson.executeUpdate(); … return;}


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Issues Regarding Example 2

Good – Created the preparedStatement once at initialization time & then binding values in function.

Loader routine purpose? – still worse performance than a SQL batch processing.

Does not check to see if account exists already.

GOOD – uses sequence number generation from oracle


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ADHOC: Java Client Example 3 Query based on Prepared Statement

{ // IN CONSTRUCTOR or INITIALIZATION BLOCK

// THE SQL QUERY TO BE MADE.String sQueryNotify="select email_author,notification,subject,s.name as name " +

" from project p, status s " +" where p.id=? " +" and s.id=p.status_id";

// CREATE A PREPARED STATEMENT, BASED ON THE ABOVE SQLm_psLookupProjectID=conn.prepareStatement(sQueryNotify);}

public EmailInfo queryEmailInfo(int id){ // BIND THE PARAMETER m_psLookupProjectID.setInt(1,id); // REUSE THE ALREADY CREATED PREPARED STATEMENT

// GET THE RESULT SET AND PROCESS IT. ResultSet rs=m_psLookupProjectID.executeQuery(); … return info;}


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ADHOC: PL/SQL Example 4PreparedStatement ps=null; sSQL=new String("declare" +

" l_id number:=0;" + " ret number:=0;" + " lssno varchar2(32):=?;" + " error_msg varchar2(1026):=null;" + " BEGIN" + " select count(*) into ret from person where SSNO= lssno ;" + " if(ret=0) then" + " insert into person(id,ssno) values(seq_id.nextval, lssno) returning id into ret;" + " end if;" + " ?:=ret;" + " EXCEPTION WHEN OTHERS THEN" + " ?:=SQLERRM;" + " END;");

ps =connection.prepareStatement(sbSQL.toString());int indx=1;

ps.setString(indx++,SSNO);

int rettype=Types.INTEGER;ps.registerOutParameter(indx++,rettype);

rettype=Types.VARCHAR;ps.registerOutParameter(indx++,rettype);

ps.executeUpdate();l_sError=ps.getString(2);if(l_sError!=null){

System.err.println("PL/SQL Error: " + l_sError); return;

}else{ ret=ps.getInt(1); System.out.println("New USERID: " + ret);}

1

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5

6

7


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Analysis of Example 4 Refer to labels in red from example. 1) Notice that "DECLARE" begins our PL/SQL code.

You don't need a DECLARE section, however, you can setup variables here by binding them to Java variables on your client side. Also notice the BEGIN statement, which is matched with the "END;" statement in #4.

DECLARE

…

BEGIN

…

END;


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Analysis of Example 4 Refer to labels in red from example. 2) Test to see if the person exists before inserting

into the table. (notice the RETURNING clause on the insert).

3) If there are any exceptions that are thrown in the surrounding block, then execute this line of code – assign the ERROR MESSAGE (SQLERRM) to the return message

4) The "END" tag is used to close the BEGIN - Also notice the usage of ";" after the END tag – also notice that we finished the string.


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Analysis of Example 4 Refer to labels in red from example. 5) Use an existing SQL connection to create the callable

statement – a prepared statement, used to bind input variables and output variables.

Notice the index variable declared and assigned value of 1.

6) Bind the SSNO string to the first occurance of a "?" in the PLSQL. (what will happen if SSNO string's length is greater than 32?).

Next few lines we register the output variables. (NOTICE how they match up with the ?).

One is of type INTEGER the other VARCHAR.


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Analysis of Example 4 Refer to labels in red from example. 7) We executed the SQL statement, and now check

for errors.

If we find an error Message (ie not null), then we will report it, and return immediately. ELSE we'll continue and report the new userid (created from a sequence number in Oracle).


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Issues from Example 4

Constructing SQL on the client side.– Need to recompile in order to change sql – Not very portable.– Not modular

Trade offs?– Plain SQL insert and catch duplicate key

exception – need to make sure your Primary KEY or unique indices are setup properly.


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FUNCTION/PROCEDURE CALL – Example 5

Call a function, that processes some data and returns a result set.

KEY THINGS TO NOTE:– Minimize SQL code on client side.– Ready for portability

– Within Oracle – yes– Using other database – perhaps– SQL 92 syntax?


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Example 5 – Syntax consideration

JDBC SYNTAX For portability

{?= call <procedure-name>[<arg1>,<arg2>, ...]} {call <procedure-name>[<arg1>,<arg2>, ...]}

ORACLE SYNTAX (not portable)

BEGIN ?:=<procedure-name>[<arg1>,<arg2>, ...]; END;


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Example 5 – PL/SQL server code

Load the following into oracle once at install time

Declare function in a package (not necessary but good to do).

CREATE OR REPLACE PACKAGE api_person_pkg ASTYPE T_REFCURSOR IS REF CURSOR; -- Define a cursor reference.

FUNCTION getPeople (VARCHAR2) RETURN T_REFCURSOR;

END api_person_pkg;/


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Example 5 – PL/SQL server code Create the body of the package/functionCREATE OR REPLACE PACKAGE BODY api_person_pkg AS

FUNCTION function getPeople(p_filter varchar2:=null) RETURN T_REFCURSOR

IS

v_ret_cursor API_PERSON_PKG.T_REFCURSOR;

BEGIN

if (p_filter is null) then

OPEN v_ret_cursor FOR

'select * from person';

else

OPEN v_ret_cursor FOR

'select * from person where username like ''%' || p_filter || '%''';

end if;

RETURN v_ret_cursor;

END;

END api_person_pkg;

/

Consider using global temporary table. Create the table at install time, then use the table to insert records into from different tables – the records are only visible to current session. On commit records go away.


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Example 5 – PLSQL

Test code to test the PL/SQLSQL> set serveroutput on;

SQL> declare

v_ret_cursor API_PERSON_PKG.T_REFCURSOR;

v_id number; --PERSON ID

v_name varchar2(120); -- the username

begin

v_ret_cursor:=API_PERSON_PKG.getPeople('jthomps');

LOOP

FETCH v_ret_cursor into v_id ,v_name;

EXIT WHEN v_ret_cursor%NOTFOUND;

dbms_output.put_line('values retrieved =' || v_id || ',' ||

v_name);

END LOOP;

END;

/


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Example 5 – java client code Call a function to return a result set.

try{

String sql=new String("{ ? = call api_person_pkg.getPeople('joelt') }");

// could have used "BEGIN ?:= api_person_pkg.getPeople('joelt'); END;"

final int cursorRefType=oracle.jdbc.driver.OracleTypes.CURSOR;

cs=m_Conn.prepareCall(sql);

cs.registerOutParameter(1,cursorRefType);

cs.execute();

rs=(ResultSet)cs.getObject(1);

int ColNameIndex=1;

ResultSetMetaData rsmd=rs.getMetaData();

String ColName1=rsmd.getColumnName(ColNameIndex++);

String ColName2=rsmd.getColumnName(ColNameIndex);

System.out.println(ColName1 + "," + ColName2);

while(rs.next())

{

l_sPersonID=rs.getString(1);

l_sUsername=rs.getString(2);

System.out.println(l_sPersonID + "," + l_sUsername);

}

}catch(SQLException sqle)

{ // ...

System.out.println("Error: " + sqle.getMessage());

}finally

{

rs.close();

cs.close();

try{ m_Conn.close(); } catch(Exception e){}

}


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Example 6 – objective

Java to insert/update record with stored procedure, showing how to create primary key & foreign key records using Oracle's sequences.


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Example 6 – create the STR_VARRAY type

You need to create a type to hold the array. This type will be referenced in the PL/SQL procedure as a parameter type, and in the Java Code.

create or replace TYPE str_varray AS VARRAY(10) OF VARCHAR2(5)

/


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Example 6 – stored procedure Create the stored procedure

PROCEDURE storePersonCar(p_username varchar2,p_Cars str_varray)AS

cnt number:=0;

id person.id%TYPE;

indx integer;

BEGIN

select count(*) into cnt from person where username=p_username;

BEGIN if ( cnt = 0 ) then

insert into person(id,username) values(seq_person_id.nextval,p_username) returning id into id; else

select id into id from person where username=p_username;delete from cars where person_id=id;

end if; indx:=p_Cars.FIRST; while indx <= p_Cars.LAST LOOP insert into cars values(id,p_Cars(indx)); indx:=p_Cars.next(indx); END LOOP;

commit;

EXCEPTION WHEN OTHERS then rollback; END; END;/


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Example 6 –Java Codeimport java.sql.*;

import oracle.sql.*;… PreparedStatement ps =null; ArrayDescriptor desc = ArrayDescriptor.createDescriptor("JOEL.STR_VARRAY", m_Conn);

String sCar=""; String cars[]=new String[10];

for(int i=0;i<10;i++) { sCar="carX"+i; // CONTRIVE A NAME of a CAR cars[i]=new String(sCar); }

ARRAY array3 = new ARRAY (desc, m_Conn, cars);

String sql=new String("{call api_person_pkg.storePersonCar('joelt',?) }");

ps= m_Conn.prepareStatement(sql);

// Set the values to insert

((oracle.jdbc.driver.OraclePreparedStatement)ps).setARRAY(1, array3);

// Insert the new row

ps.executeUpdate();

m_Conn.commit();


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Example 6 –Java Notes

Make sure to include classes12.jar and nls_charset12.jar – both found in $ORACLE_HOME/jdbc/lib directory.

This example works with Oracle 9.2.0.1.0 on Windows XP.

Java version 1.4.2_03


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Portability & Compatibility issues

SQL Standards JDBC standards Other issues (dates, functions…etc.) Portability from schema-to-schema

– abstracting calls to database with PL/SQL layer


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WRAP-UP QUESTIONS and Answers MORE INFORMATION:

– Contact: [email protected]• Or call: 530-888-6248 x205

Documents

Copyright 2004all rights reserved 1 JAVA & PL/SQL For Oracle RDBMS (8i & 9i) By Joel A. Thompson ([email protected])