EXAMPLE OF TRANSACTION package com.javasree.jdbc; import java.sql.*; import com.javasree.util.*; class TxDemo { public static void main(String as[]) { Account acc=new Account(); acc.transfer(99,88,5000); } } class Account { int bal; int dabal,sabal,danbal,sanbal; public void transfer(int sa,int da,int amt) { Connection con=null; PreparedStatement ps1=null; PreparedStatement ps2=null; try { con=DBUtil.getOracleConnection(); //start transaction con.setAutoCommit(false); //op 1 select ps1=con.prepareStatement("select bal from account where accno=?"); ps1.setInt(1,da); ResultSet rs1=ps1.executeQuery(); if(rs1.next()) { dabal=rs1.getInt(1); } else { //op 3 select ps1.setInt(1,sa); rs1=ps1.executeQuery(); if(rs1.next()) { sabal=rs1.getInt(1); } else { throw new Exception(); } if(sabal>=amt) { sanbal=sabal-amt; } else { throw new Exception(); } //op4 update ps2.setInt(1,sanbal); ps2.setInt(2,sa); ps2.executeUpdate(); con.commit(); } catch(Exception e) { try { con.rollback(); } catch(Exception e1){ } System.out.println(e); } finally { DBUtil.cleanup(con,ps1); } } } Transaction Acct_Transact ion Acct_Transact ion
