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* undocumented feature or bug in subquery : psql (PostgreSQL) 9.4.6 on SLES12 SP1
@ 2016-08-25 16:29 otter117@yahoo.de
0 siblings, 1 reply; 2+ messages in thread
From: otter117@yahoo.de @ 2016-08-25 16:29 UTC (permalink / raw)
To: pgsql-docs
The following documentation comment has been logged on the website:
Page: https://www.postgresql.org/docs/9.4/static/functions-subquery.html
Description:
psql (PostgreSQL) 9.4.6 on SLES12 SP1
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)
Get an error on this one ERROR: column b.foo does not exist
SELECT foo,bar FROM a WHERE foo=1 AND bar NOT IN (SELECT bar FROM b WHERE
b.bar > 2 AND b.foo=2)
It works if I remove foo from the subquery.
SELECT foo,bar FROM a WHERE foo=1 AND bar NOT IN (SELECT bar FROM b WHERE
b.bar > 2)
Do I need to qualify all columns in the subquery or is this a bug is psql
9.4.6?
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* Re: undocumented feature or bug in subquery : psql (PostgreSQL) 9.4.6 on SLES12 SP1
@ 2016-08-26 13:07 Tom Lane <tgl@sss.pgh.pa.us>
parent: otter117@yahoo.de
0 siblings, 0 replies; 2+ messages in thread
From: Tom Lane @ 2016-08-26 13:07 UTC (permalink / raw)
To: otter117@yahoo.de; +Cc: pgsql-docs
otter117@yahoo.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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2016-08-25 16:29 undocumented feature or bug in subquery : psql (PostgreSQL) 9.4.6 on SLES12 SP1 otter117@yahoo.de
2016-08-26 13:07 ` Tom Lane <tgl@sss.pgh.pa.us>
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