import { BaseDbField } from '../fields/base' ; export class Expression { constructor ( ) { } } export class ColExpression extends Expression { alias : string ; colName : string ; constructor ( alias , colName ) { super ( ) ; this . alias = alias ; this . colName = colName ; } } export class Col extends ColExpression { target : BaseDbField ; constructor ( alias , target ) { super ( alias , target . name ) ; this . target = target ; } } export class Star extends Expression { }