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Posted by strawberry on 08/17/06 11:15
MH wrote:
> hi everyone !
>
> I am working on a MySQL database version 3.23.58 .
>
> I want to get the customers who have the same email address. Here is what I
> did :
>
> SELECT C1.Username, C1.Email, COUNT(*) FROM customer AS C1, customer AS C2
> WHERE C1.Email = C2.Email GROUP BY C1.CustomerID HAVING COUNT(*) > 1
>
> The query does its job but is veerryyyyy slow to execute although I have
> only 5000 records in my database.
>
> Any idea how to optimize this query ?
>
> Thanks a lot !
>
> MH
How slow is slow? Does it take more than a second? Also, is there an
index on Email? This may make a difference - although when I tested
your query on a (smaller) sample it was actually slower WITH the index!
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