Details
Description
(I've found this issue when fixing MDEV-25202. the fix is a part of MDEV-25202 fix )
ON expressions inside a join nest cannot refer to tables outside the nest. This can be "circumvented" by putting the outside reference into a subquery.
create table t1 (a int, b int); |
create table t2 (c int, d int); |
create table t3 (e int, f int); |
create table t4 (g int, h int); |
A reference to t1.a in the ON expression produces an error, as expected:
explain
|
select * |
from |
t1 left join |
(t2
|
join |
t3 on |
(t3.f=t1.a)
|
) on (t2.c=t1.a ); |
ERROR 1054 (42S22): Unknown column 't1.a' in 'on clause'
|
A reference from a subquery does not produce an error:
explain
|
select * |
from |
t1 left join |
(t2
|
join |
t3 on |
(t3.f=(select max(g) from t4 where t4.h=t1.a)) |
) on (t2.c=t1.a ); |
This is wrong/
Attachments
Issue Links
- relates to
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MDEV-25346 Server crashes in Item_field::fix_outer_field upon subquery with unknown column
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- Closed
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