Insert,Update,Retrive using stored procedures or functions in mysql

Question

Check whether the primary key exists in the table.

1. If exists retrieve three column values and update the three column values with new values.

   String sql = "SELECT brno, brdate, type1,type,flag,mcode,pamount,tax,pamount1,liab FROM rawdata WHERE mcode="+mcode;
   
   ResultSet rs = statement.executeQuery(sql);
   
   rs.first();
   float oldPamount= rs.getFloat("pamount");
   float tax= rs.getFloat("tax");
   float oldPamount1= rs.getFloat("pamount1");
   
   float newPamount= pamount;
   float newTax= tax;
   float newPamount1= pamount1;
   rs.updateFloat("pamount", newPamount);
   rs.updateFloat("tax", newTax);
   rs.updateFloat("pamount1", newPamount1);
   rs.updateRow();
   

2. If not exists insert the record and retrieve it. I have tried this:

   INSERT INTO rawdata (brno, brdate, type1,type,flag,mcode,pamount,tax,pamount1,liab)
   
   SELECT * FROM (SELECT '1', '02.05.15', 'G','H','E','2222','789.00','0.00','789.00','L') AS tmp
           WHERE NOT EXISTS (
               SELECT mcode FROM rawdata WHERE mcode = '2222'
           );
   

But it getting the following error duplicate value 789.00

I need to done these things at a time not separate queries.

This is my table(rawdata) with fields(brno, brdate, type1,type,flag,mcode,pamount,tax,pamount1,liab) where mcode is the primarykey

Here the pamount,tax,pamount1 need to be updated if the record exists.

For Ex:

These are the sample values 873.00,0.00,873.00 needed to be updated to 789.00,0.00,789.00 (or) 24000.00,240.00,23760.00

Other wise need to insert entire row for the new mcode

I have tried the above queries, but i need to be done at time.