Update query is wrong?

[sahar sa]

Hi,
Im having problem with this Update query, I dont know what is wrong? I checked with sun but couldnt find any thing different. still got error!
any idea?
here is the code:

public static void update( String PO,  String A, double Value){
        PreparedStatement pstmt = null;
        ResultSet rows ;
        try{
            Connection con = getConnection();
            StringBuilder query = new StringBuilder() ; 
            if(A=="Acon"){
            query.append("update PO set Acon=?").append(" where PO=?");}
            else if(A=="Anon"){
            query.append("update PO set Anon=?").append(" where PO=?");}
            String update = query.toString();
            pstmt = con.prepareStatement(update);
            pstmt.setDouble(1,Value);
            pstmt.setString(2,PO);    
            int result = pstmt.executeUpdate(update);      
            System.out.println("Good has been UPDATED in PO. ");
             pstmt.close();
             con.close(); 
           }catch(Exception ex){
                  ex.printStackTrace();}
}

and error:

   com.mysql.jdbc.exceptions.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '? where PO=?' at line 1
        at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:936)
        at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2985)
        at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1631)
        at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1723)
        at com.mysql.jdbc.Connection.execSQL(Connection.java:3277)
        at com.mysql.jdbc.Statement.executeUpdate(Statement.java:1402)
        at com.mysql.jdbc.Statement.executeUpdate(Statement.java:1317)
        at DB.PO.update(PO.java:176)
        at DB.main.main(main.java:162)
 

Thank you so much!
Sahar.

[Srikkanth Mohanasundaram]

  if(A=="Acon"){      

I guess this is the problem.
Change this to

  if(A.equals("Acon")){      

Thanks,
Srikkanth

[sahar sa]

I find the answer:
the three methods execute, executeQuery, and executeUpdate are modified so that they take no argument:
source:
http://java.sun.com/j2se/1.4.2/docs/guide/jdbc/getstart/preparedstatement.html
thanks,
Sahar.

[Satya Maheshwari]

If that is the case, did your code even compile?