having for aggregate field alias name bug

[siddontang]

create table t1 (a int, b int) engine=innodb;
insert into t1 values (1,2), (1,3), (2,3), (2,4), (2,5), (3,4), (4,5), (4,100);

mysql> select a, sum(b) as b from t1 group by a having b > 4;
+------+------+
| a    | b    |
+------+------+
|    1 |    5 |
|    2 |   12 |
|    4 |  105 |
+------+------+

but we only get one row result.

[xwb1989]

A simpler test case is:
select a as b from t1 having b > 4;
mysql gives
empty set
but TiDB gives

+---+
| b |
+---+
| 2 |
| 4 |
| 4 |
+---+

[qiuyesuifeng]

@xwb1989 Thanks for report.
Yes, that is a problem.
I will fix it later.

[xwb1989]

Following is problematic in HavingRset.CheckAndUpdateSelectList, :

if field.ContainFieldName(name, selectList.ResultFields, field.OrgFieldNameFlag) {
    continue
}       
if field.ContainFieldName(name, selectList.ResultFields, field.FieldNameFlag) {
    if field.ContainFieldName(name, tableFields, field.OrgFieldNameFlag) {
        selectList.CloneHiddenField(name, tableFields)
    }
    continue
}

not having enough time to really dig into yet, but commenting out

    if field.ContainFieldName(name, tableFields, field.OrgFieldNameFlag) {
        selectList.CloneHiddenField(name, tableFields)
    }

Can solve this particular problem(but might break others :(

Just FYI

[qiuyesuifeng]

@xwb1989
Thanks for your suggestion.

We used hidden fields for having fields which not in select or group by fields, and we have not distinguished aggregate and none aggregate fields, so we have the problem as @siddontang mentioned.

As for select a as b from t1 having b > 4;, because some having conditions has some confused results, like select a as b from t1 having b + 1 or select a as b from t1 having a + b or select a + b as b from t1 having a + b > 0 and so on, now we only process alias field as origin field first, so select a as b from t1 having b > 4; may equal to select a from (select a, b from t1 having b > 4) c;.

Later we will discuss and fix this problem.
Thanks again.

[qiuyesuifeng]

@xwb1989
We have fixed this problem, u can update master branch and have a try:)

[xwb1989]

Thank you for letting me know :)

[xwb1989]

I could confirm that the test cases mentioned above is passing.

[siddontang]

Cool @xwb1989