func (v *havingVisitor) checkIdentInGroupBy(i *expression.Ident) (*expression.Ident, bool, error) {
for _, by := range v.groupBy {
e := castIdent(by)
if e == nil {
// group by must be a identifier too
continue
}
if !field.CheckFieldsEqual(e.L, i.L) {
// not same, continue
continue
}
// if group by references select list or having is qualified identifier,
// no other check.
if e.ReferScope == expression.IdentReferSelectList || field.IsQualifiedName(i.L) {
i.ReferScope = e.ReferScope
i.ReferIndex = e.ReferIndex
return i, true, nil
}
// having is unqualified name, e.g, select * from t1, t2 group by t1.c having c.
// both t1 and t2 have column c, we must check ambiguous here.
idx := field.GetResultFieldIndex(i.L, v.selectList.FromFields)
if len(idx) > 1 {
return i, false, errors.Errorf("Column '%s' in having clause is ambiguous", i)
}
i.ReferScope = e.ReferScope
i.ReferIndex = e.ReferIndex
return i, true, nil
}
return i, false, nil
}
func (v *havingVisitor) visitIdentInAggregate(i *expression.Ident) (expression.Expression, error) {
// if we are visiting aggregate function arguments, the identifier first checks in from table,
// then in select list, and outer query finally.
// find this identifier in FROM.
idx := field.GetResultFieldIndex(i.L, v.selectList.FromFields)
if len(idx) > 0 {
i.ReferScope = expression.IdentReferFromTable
i.ReferIndex = idx[0]
return i, nil
}
// check in select list.
index, err := checkIdentAmbiguous(i, v.selectList, HavingClause)
if err != nil {
return i, errors.Trace(err)
}
if index >= 0 {
// find in select list
i.ReferScope = expression.IdentReferSelectList
i.ReferIndex = index
return i, nil
}
// TODO: check in out query
// TODO: return unknown field error, but now just return directly.
// Because this may reference outer query.
return i, nil
}
func (v *groupByVisitor) VisitIdent(i *expression.Ident) (expression.Expression, error) {
// Group by ambiguous rule:
// select c1 as a, c2 as a from t group by a is ambiguous
// select c1 as a, c2 as a from t group by a + 1 is ambiguous
// select c1 as c2, c2 from t group by c2 is ambiguous
// select c1 as c2, c2 from t group by c2 + 1 is not ambiguous
var (
index int
err error
)
if v.rootIdent == i {
// The group by is an identifier, we must check it first.
index, err = checkIdentAmbiguous(i, v.selectList, GroupByClause)
if err != nil {
return nil, errors.Trace(err)
}
}
// first find this identifier in FROM.
idx := field.GetResultFieldIndex(i.L, v.selectList.FromFields)
if len(idx) > 0 {
i.ReferScope = expression.IdentReferFromTable
i.ReferIndex = idx[0]
return i, nil
}
if v.rootIdent != i {
// This identifier is the part of the group by, check ambiguous here.
index, err = checkIdentAmbiguous(i, v.selectList, GroupByClause)
if err != nil {
return nil, errors.Trace(err)
}
}
// try to find in select list, we have got index using checkIdent before.
if index >= 0 {
// group by can not reference aggregate fields
if _, ok := v.selectList.AggFields[index]; ok {
return nil, errors.Errorf("Reference '%s' not supported (reference to group function)", i)
}
// find in select list
i.ReferScope = expression.IdentReferSelectList
i.ReferIndex = index
return i, nil
}
// TODO: check in out query
return i, errors.Errorf("Unknown column '%s' in 'group statement'", i)
}
func (v *havingVisitor) checkIdentInSelectList(i *expression.Ident) (*expression.Ident, bool, error) {
index, err := checkIdentAmbiguous(i, v.selectList, HavingClause)
if err != nil {
return i, false, errors.Trace(err)
}
if index >= 0 {
// identifier references a select field. use it directly.
// e,g. select c1 as c2 from t having c2, here c2 references c1.
i.ReferScope = expression.IdentReferSelectList
i.ReferIndex = index
return i, true, nil
}
lastIndex := -1
var lastFieldName string
// we may meet this select c1 as c2 from t having c1, so we must check origin field name too.
for index := 0; index < v.selectList.HiddenFieldOffset; index++ {
e := castIdent(v.selectList.Fields[index].Expr)
if e == nil {
// not identifier
continue
}
if !field.CheckFieldsEqual(e.L, i.L) {
// not same, continue
continue
}
if field.IsQualifiedName(i.L) {
// qualified name, no need check
i.ReferScope = expression.IdentReferSelectList
i.ReferIndex = index
return i, true, nil
}
if lastIndex == -1 {
lastIndex = index
lastFieldName = e.L
continue
}
// we may meet select t1.c as a, t2.c as b from t1, t2 having c, must check ambiguous here
if !field.CheckFieldsEqual(lastFieldName, e.L) {
return i, false, errors.Errorf("Column '%s' in having clause is ambiguous", i)
}
i.ReferScope = expression.IdentReferSelectList
i.ReferIndex = index
return i, true, nil
}
if lastIndex != -1 {
i.ReferScope = expression.IdentReferSelectList
i.ReferIndex = lastIndex
return i, true, nil
}
return i, false, nil
}
func (v *fromIdentVisitor) VisitIdent(i *expression.Ident) (expression.Expression, error) {
idx := field.GetResultFieldIndex(i.L, v.fromFields, field.DefaultFieldFlag)
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)
}
if v.clause == onClause {
// on clause can't check outer query.
return nil, errors.Errorf("Unknown column '%s' in '%s'", i, v.clause)
}
// TODO: check in outer query
return i, nil
}
func (v *orderByVisitor) VisitIdent(i *expression.Ident) (expression.Expression, error) {
// Order by ambiguous rule:
// select c1 as a, c2 as a from t order by a is ambiguous
// select c1 as a, c2 as a from t order by a + 1 is ambiguous
// select c1 as c2, c2 from t order by c2 is ambiguous
// select c1 as c2, c2 from t order by c2 + 1 is not ambiguous
// Order by identifier reference check
// select c1 as c2 from t order by c2, c2 in order by references c1 in select field.
// select c1 as c2 from t order by c2 + 1, c2 in order by c2 + 1 references t.c2 in from table.
// select c1 as c2 from t order by sum(c2), c2 in order by sum(c2) references t.c2 in from table.
// select c1 as c2 from t order by sum(1) + c2, c2 in order by sum(1) + c2 references t.c2 in from table.
// select c1 as a from t order by a, a references c1 in select field.
// select c1 as a from t order by sum(a), a in order by sum(a) references c1 in select field.
// TODO: unify VisitIdent for group by and order by visitor, they are little different.
var (
index int
err error
)
if v.rootIdent == i {
// The order by is an identifier, we must check it first.
index, err = checkIdentAmbiguous(i, v.selectList, OrderByClause)
if err != nil {
return nil, errors.Trace(err)
}
if index >= 0 {
// identifier references a select field. use it directly.
// e,g. select c1 as c2 from t order by c2, here c2 references c1.
i.ReferScope = expression.IdentReferSelectList
i.ReferIndex = index
return i, nil
}
}
// find this identifier in FROM.
idx := field.GetResultFieldIndex(i.L, v.selectList.FromFields)
if len(idx) > 0 {
i.ReferScope = expression.IdentReferFromTable
i.ReferIndex = idx[0]
return i, nil
}
if v.rootIdent != i {
// This identifier is the part of the order by, check ambiguous here.
index, err = checkIdentAmbiguous(i, v.selectList, OrderByClause)
if err != nil {
return nil, errors.Trace(err)
}
}
// try to find in select list, we have got index using checkIdentAmbiguous before.
if index >= 0 {
// find in select list
i.ReferScope = expression.IdentReferSelectList
i.ReferIndex = index
return i, nil
}
// TODO: check in out query
return i, errors.Errorf("Unknown column '%s' in 'order clause'", i)
}