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Am 29.09.2005 um 12:03 schrieb Richard Huxton:
Axel Rau wrote:
Am 29.09.2005 um 10:30 schrieb Richard Huxton:
Axel Rau wrote:
...
Ah - this is two questions:
1. What are the unique (t2_name,t1_name) pairings?
2. How many different (t1.id) values are there for each t2.
So - something like:
SELECT names.T2_name, names.T1_name, counts.num_t2
FROM
(
SELECT DISTINCT T2.T2_name, T1.T1_name
FROM T2,T1
WHERE T2.id = T1.fk_t2
) AS names,
(
SELECT T2.T2_name, COUNT(T1.id) AS num_t2
FROM T2, T1
WHERE T2.id = T1.fk_t2
GROUP BY T2.T2_name
HAVING COUNT(T1.id) > 1
) AS counts
WHERE
names.T2_name = counts.T2_name
;
You could write the "names" sub-query with a GROUP BY if you wanted of
course.
Exactly, that query works as I expected. Thank you.
Can you answer this question as well:
Looking for a workaround, I learned that aggregate functions are not
allowed in WHERE clauses.
Question: Is this conform with the standard?
Axel
Axel Rau, Frankfurt, Germany +49-69-951418-0
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TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
