Re: Selecting count of details along with details columns

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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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