BloodLoss:

String id = (jTable1.getValueAt(row, 4).toString());

int x = JOptionPane.showConfirmDialog(this, "Do You Want To Delete This Author ?", "Confirmation", JOptionPane.YES_NO_OPTION);  

if (x == 0) {

    try{

          ResultSet code = DB.getdata("SELECT bm_id FROM book_master WHERE au_id='"+id+"'");

          if(**code.next()**){

          DB.setdata("UPDATE author SET activestatus='0' WHERE author_id='"+id+"'"); 
          }

          else{

          DB.setdata("DELETE  FROM author WHERE author_id='"+id+"'"); 
          }