public Db(Connection conn){
  try {
    this.conn=conn;
    stat=conn.createStatement();
  }
 catch (  SQLException e) {
    throw convert(e);
  }
}

public Db ( Connection conn ) { try { this . conn = conn ; stat = conn . createStatement ( ) ; } catch ( SQLException e ) { throw convert ( e ) ; } }
create a database object using the given connection .
