*: add more clause type

plan/plans/select_list.go

@@ -124,24 +124,6 @@ func (s *SelectList) UpdateAggFields(expr expression.Expression) (expression.Exp
 	return &expression.Position{N: index + 1, Name: name}, nil
 }
 
-// CloneHiddenField checks and clones field and result field from table fields,
-// and adds them to hidden field of select list.
-func (s *SelectList) CloneHiddenField(name string, tableFields []*field.ResultField) bool {
-	// Check and add hidden field.
-	if field.ContainFieldName(name, tableFields, field.CheckFieldFlag) {
-		resultField, _ := field.CloneFieldByName(name, tableFields, field.CheckFieldFlag)
-		f := &field.Field{
-			Expr: &expression.Ident{
-				CIStr: resultField.ColumnInfo.Name,
-			},
-		}
-		s.AddField(f, resultField)
-		return true
-	}
-
-	return false
-}
-
 // CheckReferAmbiguous checks whether an identifier reference is ambiguous or not in select list.
 // e,g, "select c1 as a, c2 as a from t group by a" is ambiguous,
 // but "select c1 as a, c1 as a from t group by a" is not.
@@ -235,6 +217,7 @@ func ResolveSelectList(selectFields []*field.Field, srcFields []*field.ResultFie
 			continue
 		}
 
+		// TODO: use fromIdentVisitor to cleanup.
 		var result *field.ResultField
 		for _, name := range names {
 			idx := field.GetResultFieldIndex(name, srcFields, field.DefaultFieldFlag)

rset/rsets/fields.go

@@ -40,7 +40,7 @@ type SelectFieldsRset struct {
 }
 
 func updateSelectFieldsRefer(selectList *plans.SelectList) error {
-	visitor := newFromIdentVisitor(selectList.FromFields)
+	visitor := newFromIdentVisitor(selectList.FromFields, fieldListClause)
 
 	// we only fix un-hidden fields here, for hidden fields, it should be
 	// handled in their own clause, in order by or having.

rset/rsets/helper.go

@@ -50,13 +50,22 @@ type clauseType int
 
 const (
 	noneClause clauseType = iota
+	onClause
+	whereClause
 	groupByClause
-	orderByClause
+	fieldListClause
 	havingClause
+	orderByClause
 )
 
 func (clause clauseType) String() string {
 	switch clause {
+	case onClause:
+		return "on clause"
+	case fieldListClause:
+		return "field list"
+	case whereClause:
+		return "where clause"
 	case groupByClause:
 		return "group statement"
 	case orderByClause:
@@ -138,24 +147,28 @@ func checkIdent(i *expression.Ident, selectList *plans.SelectList, clause clause
 type fromIdentVisitor struct {
 	expression.BaseVisitor
 	fromFields []*field.ResultField
+	clause     clauseType
 }
 
 func (v *fromIdentVisitor) VisitIdent(i *expression.Ident) (expression.Expression, error) {
 	idx := field.GetResultFieldIndex(i.L, v.fromFields, field.DefaultFieldFlag)
-	if len(idx) > 0 {
+	if len(idx) == 1 {
 		i.ReferScope = expression.IdentReferFromTable
 		i.ReferIndex = idx[0]
 		return i, nil
+	} else if len(idx) > 1 {
+		return nil, errors.Errorf("Column '%s' in %s is ambiguous", i, v.clause)
 	}
 
 	// TODO: check in outer query
 	return i, nil
 }
 
-func newFromIdentVisitor(fromFields []*field.ResultField) *fromIdentVisitor {
+func newFromIdentVisitor(fromFields []*field.ResultField, clause clauseType) *fromIdentVisitor {
 	visitor := &fromIdentVisitor{}
 	visitor.BaseVisitor.V = visitor
 	visitor.fromFields = fromFields
+	visitor.clause = clause
 
 	return visitor
 }

rset/rsets/where.go

@@ -180,7 +180,7 @@ func (r *WhereRset) planStatic(ctx context.Context, e expression.Expression) (pl
 }
 
 func (r *WhereRset) updateWhereFieldsRefer() error {
-	visitor := newFromIdentVisitor(r.Src.GetFields())
+	visitor := newFromIdentVisitor(r.Src.GetFields(), whereClause)
 
 	e, err := r.Expr.Accept(visitor)
 	if err != nil {