public SelectClause add(Expression expression,String asName){
  selectList.add(new SelectClauseExpression(expression,asName));
  return this;
}

public SelectClause add ( Expression expression , String asName ) { selectList . add ( new SelectClauseExpression ( expression , asName ) ) ; return this ; }
adds an expression to the select clause and an " as " - asname for the column .
