示例#1
0
// Do the real work to evaluate subquery.
func (e *Evaluator) subqueryExec(v ast.SubqueryExec) bool {
	rowCount := 2
	if e.multipleRows {
		rowCount = -1
	} else if e.existRow {
		rowCount = 1
	}
	rows, err := v.EvalRows(e.ctx, rowCount)
	if err != nil {
		e.err = errors.Trace(err)
		return false
	}
	if e.multipleRows || e.existRow {
		v.SetValue(rows)
		return true
	}
	switch len(rows) {
	case 0:
		v.SetValue(nil)
	case 1:
		v.SetValue(rows[0])
	default:
		e.err = errors.New("Subquery returns more than 1 row")
		return false
	}
	return true
}
示例#2
0
文件: evaluator.go 项目: astaxie/tidb
// Do the real work to evaluate subquery.
func (e *Evaluator) subqueryExec(v ast.SubqueryExec) bool {
	rowCount := 2
	if e.multipleRows {
		rowCount = -1
	} else if e.existRow {
		rowCount = 1
	}
	rows, err := v.EvalRows(e.ctx, rowCount)
	if err != nil {
		e.err = errors.Trace(err)
		return false
	}
	if e.multipleRows || e.existRow {
		v.GetDatum().SetInterface(types.MakeDatums(rows...))
		return true
	}
	switch len(rows) {
	case 0:
		v.GetDatum().SetNull()
	case 1:
		v.SetDatum(types.NewDatum(rows[0]))
	default:
		e.err = errors.New("Subquery returns more than 1 row")
		return false
	}
	return true
}