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Query with Count Embedded

Posted on 2004-10-08
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Last Modified: 2008-02-26
Here's what I want to do spelled out in "English".  I'm having trouble converting this to SQL ...

SELECT USER_ID, DATE FROM CLASSES_TAKEN WHERE USER_ID IN (SELECT USER_ID FROM AWARDS WHERE USER_ID APPEARS ONLY ONCE IN THE AWARDS TABLE)

Obviously "appears only once in the Awards table" isn't valid SQL Syntax, but that's the spelled out version.

Help!
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Question by:UPRRDevelopers
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dramacqueen earned 50 total points
ID: 12259335
Hi UPRRDevelopers,

You need a nested sql something like
SELECT USER_ID, DATE FROM CLASSES_TAKEN WHERE USER_ID IN (
    SELECT USER_ID FROM AWARDS WHERE (USER_ID, 1) in (
        select user_id, count(*) from awards
        group by user_id)
    );
NB you can use this for any particular count of records by changing the '1' in the 2nd line
Hope it helps, have a nice weekend.
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Expert Comment

by:andrewst
ID: 12259389
More simply:

SELECT USER_ID, DATE FROM CLASSES_TAKEN WHERE USER_ID IN (
        select user_id
        from awards
        group by user_id
        having count(*) = 1);
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