return sqlFnTrim
	case e.DateAdd != nil:
		return sqlFnDateAdd
	case e.DateDiff != nil:
		return sqlFnDateDiff
	default:
		return ""
	}
}

// evalSQLFnNode assumes that the FuncExpr is not an aggregation
// function.
func (e *FuncExpr) evalSQLFnNode(r Record, tableAlias string) (res *Value, err error) {
	// Handle functions that have phrase arguments
	switch e.getFunctionName() {
	case sqlFnCast:
		expr := e.Cast.Expr

func (e *FuncExpr) evalNode(r Record, tableAlias string) (res *Value, err error) {
	switch e.getFunctionName() {
	case aggFnCount, aggFnAvg, aggFnMax, aggFnMin, aggFnSum:
		return e.getAggregate()
	default:
		return e.evalSQLFnNode(r, tableAlias)
	}
}

// evalNode on a literal value is independent of the node being an
// aggregation or a row function - it always returns a value.