Lines after the executeQuery(quer) not executing?

Question

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         
   String del_user = JOptionPane.showInputDialog(null,"Enter the Username To be deleted     :"  ,"Delete User !", JOptionPane.WARNING_MESSAGE);

   try {    
      stmt = con.createStatement(); 
      String quer = "delete from Udet where username='"+del_user+"'";
      rs=stmt.executeQuery(quer);

      int count=0; 
      while(rs.next())
      {
         count++;
     }

     if(count==1)
     {
        JOptionPane.showMessageDialog(null,"The user has been deleted");
     }

     else
     {
        JOptionPane.showMessageDialog(null,"No such User Exists");
     }

  } catch(Exception e){}


}        

THE QUERY EXECUTES FINE ! THE RECORD GETS DELETED BUT THE LINES AFTER QUERYEXECUTION ARE NOT EXECUTING ... the JOptionPane will work after the try block but then the value of count wont be determined...

Answer 1

A DELETE statement doesn't return a ResultSet and therefore you should use the method stmt.executeUpdate(quer); instead of stmt.executeQuery(quer);. One way you can see how many results were deleted from the query is run a SELECT COUNT(*) query on the table before and after the DELETE using the executeQuery() method which will both times return a ResultSet with a single result containing how many records the table contains. After running it before and after the DELETE you can compare the 2 numbers. The result will probably be a String but you can just use int integer = Integer.parseInt(String); to get the int from it. The code should look like this:

stmt = "SELECT COUNT(*) AS Count FROM table_name";
int initialSize = 0;
rs = stmt.executeQuery(stmt);
while(rs.next){
  initialSize = Integer.parseInt(rs.getString("Count");
}

Run the DELETE query and then repeat the COUNT query passing the int into a new variable (for this answer I'll call it newSize) so the number of changes the DELETE made would be:

int changesMade = initialSize - newSize;