From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | otter117(at)yahoo(dot)de |
Cc: | pgsql-docs(at)postgresql(dot)org |
Subject: | Re: undocumented feature or bug in subquery : psql (PostgreSQL) 9.4.6 on SLES12 SP1 |
Date: | 2016-08-26 13:07:14 |
Message-ID: | 26546.1472216834@sss.pgh.pa.us |
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Lists: | pgsql-docs |
otter117(at)yahoo(dot)de writes:
> 2 tables a and b
> Table "public.a"
> Column | Type | Modifiers
> -----------------+--------------------------+---------------
> foo | integer | not null
> bar | integer | not null
> Table "public.b"
> Column | Type | Modifiers
> -----------------+--------------------------+---------------
> bar | integer | not null
> No error when executing this statement even though table b does not contain
> column foo
> SELECT foo,bar FROM a WHERE foo=1 AND bar NOT IN (SELECT bar FROM b WHERE
> bar > 2 AND foo=2)
No, but table a does, and that's a legal outer reference per the SQL
standard. This is neither a bug nor undocumented.
> Do I need to qualify all columns in the subquery or is this a bug is psql
> 9.4.6?
It's often wise to qualify column references in multi-table queries
(subqueries or not) to ensure they are referencing what you think
they're referencing.
regards, tom lane
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