copyright 2004all rights reserved 1 JAVA & PL/SQL For Oracle RDBMS (8i & 9i) By Joel A. Thompson 05/2004

copyright 2004 all rights reserved 2 INTRODUCTION Joel A. Thompson 15 years of industry experience Consultant: Architecture, Software Engineering and Project Manager Java and Oracle expert

copyright 2004 all rights reserved 3 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

copyright 2004 all rights reserved 4 Getting Started with Java Must install a JDK & IDE –JDK (Java Developers Kit) from Sun –IDE (Integrated Developers Environment) Oracle’s JDeveloper (technet.oracle.com) IntelliJ: ( Textpad:

copyright 2004 all rights reserved 5 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:

copyright 2004 all rights reserved 6 Client Server Java/PLSQL Architecture

copyright 2004 all rights reserved 7 What is PL/SQL? A programming language –If/then/else –Loops –Function calls –Transactional –Procedural Feature rich Performance Gain Oracle only

copyright 2004 all rights reserved 8 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.

copyright 2004 all rights reserved 9 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.

copyright 2004 all rights reserved 10 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 + "'");

copyright 2004 all rights reserved 11 Issues Regarding Example 1 Selecting from entire table is generally a bad idea. (unless small "lookup table"). One call for the Query, and 2 nd call to create the account.

copyright 2004 all rights reserved 12 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 SQL m_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; }

copyright 2004 all rights reserved 13 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

copyright 2004 all rights reserved 14 ADHOC: Java Client Example 3 Query based on Prepared Statement { // IN CONSTRUCTOR or INITIALIZATION BLOCK // THE SQL QUERY TO BE MADE. String sQueryNotify="select _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 SQL m_psLookupProjectID=conn.prepareStatement(sQueryNotify); } public Info query Info(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; }

copyright 2004 all rights reserved 15 ADHOC: PL/SQL Example 4 PreparedStatement 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); }

copyright 2004 all rights reserved 16 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;

copyright 2004 all rights reserved 17 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.

copyright 2004 all rights reserved 18 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.

copyright 2004 all rights reserved 19 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).

copyright 2004 all rights reserved 20 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.

copyright 2004 all rights reserved 21 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?

copyright 2004 all rights reserved 22 Example 5 – Syntax consideration JDBC SYNTAX For portability {?= call [,,...]} {call [,,...]} ORACLE SYNTAX (not portable) BEGIN ?:= [,,...]; END;

copyright 2004 all rights reserved 23 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 AS TYPE T_REFCURSOR IS REF CURSOR; -- Define a cursor reference. FUNCTION getPeople (VARCHAR2) RETURN T_REFCURSOR; END api_person_pkg; /

copyright 2004 all rights reserved 24 Example 5 – PL/SQL server code Create the body of the package/function CREATE 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.

copyright 2004 all rights reserved 25 Example 5 – PLSQL Test code to test the PL/SQL SQL> 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; /

copyright 2004 all rights reserved 26 Example 5 – java client code Call a function to return a result set. t ry { 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){} }

copyright 2004 all rights reserved 27 Example 6 – objective Java to insert/update record with stored procedure, showing how to create primary key & foreign key records using Oracle's sequences.

copyright 2004 all rights reserved 28 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) /

copyright 2004 all rights reserved 29 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; /

copyright 2004 all rights reserved 30 Example 6 –Java Code import 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();

copyright 2004 all rights reserved 31 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 on Windows XP. Java version 1.4.2_03

copyright 2004 all rights reserved 32 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

copyright 2004 all rights reserved 33 WRAP-UP QUESTIONS and Answers MORE INFORMATION: –Contact: Or call: x205