DISTINCT key_field is fine. I don't think it will make a difference. My example was using only one field.

Paul DuBois wrote:

At 4:22 PM -0500 9/18/03, Allen wrote:

Ok. I looked through google and saw a couple examples of how to find the duplicates in a table that looked like this...

SELECT date, time, id, count(*) as n from session GROUP BY date,time,id
HAVING n > 1;

Ok. So I tried it. I have a table of 13,128,178 rows (not a small example). I ran a DISTINCT on the key field and the result was 12,787,768 so that tells


Do you mean "key field" (singular) or do you really mean
DISTINCT date, time, id ?

me there are 340,410 duplicate rows.

Ok. I run the above command. I get 272,626 as an answer. What? That doesn't match. For grins I run the query again with.

HAVING n > 2;

This time I get 67,756.
Again HAVING n > 3 I get 30.

Add them all up I get 340,413. Now they match! What seems to be happening is that the HAVING n > 1 is really doing n == 2 not GREATER than 1 and so on.

I would say this looks like a bug or I am crazy either of which could be true.

- Allen




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Allen Brost
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