From: | Joachim Trinkwitz <jtr(at)uni-bonn(dot)de> |
---|---|
To: | pgsql-sql(at)postgresql(dot)org |
Subject: | Aggregates not allowed in WHERE clause? |
Date: | 2002-06-19 08:04:24 |
Message-ID: | 874rfzr8xj.fsf@waffel.germanistik.uni-bonn.de |
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Thread: | |
Lists: | pgsql-sql |
Hi all,
I have a table (lv) with a field "semester" and I'm trying to fish out all
rows which have a value corresponding to a max() value of another
table's (lf_sem) "semester" field. The intention is to keep a value
with the current term in lf_sem so I can get all rows which concern
this term.
Example tables:
lv
==
semester | kvvnr
---------+------
2001ss | 4185
2001ss | 4203
2002ws | 4163
2002ws | 4190
lf_sem
======
semester
--------
2001ws
2002ss
2002ws
At first I tried this query:
SELECT kvvnr
FROM lv, lf_sem
WHERE lv.semester = max(lf_sem.semester);
This yields the message: 'Aggregates not allowed in WHERE clause'.
Next I tried this one:
SELECT kvvnr, max(lf_sem.semester) AS akt_semester
FROM lv, lf_sem
WHERE lv.semester = akt_semester;
Now I got: 'Attribute 'akt_semester' not found'
Is there another way to get what I want?
Clueless,
joachim
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