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Revision: 24309
at February 25, 2010 16:29 by jmiller
Updated Code 
# Suppose you want to find all email addresses in a table that exist more than once:

SELECT email, 
 COUNT(email) AS count
FROM users
GROUP BY email
HAVING ( COUNT(email) > 1 )


# You could also use this technique to find rows that occur exactly once:

SELECT email
FROM users
GROUP BY email
HAVING ( COUNT(email) = 1 )

Revision: 24308
at February 25, 2010 16:29 by jmiller
Initial Code 
Suppose you want to find all email addresses in a table that exist more than once:

SELECT email, 
 COUNT(email) AS count
FROM users
GROUP BY email
HAVING ( COUNT(email) > 1 )


You could also use this technique to find rows that occur exactly once:

SELECT email
FROM users
GROUP BY email
HAVING ( COUNT(email) = 1 )
Initial URL 
http://www.petefreitag.com/item/169.cfm
Initial Description 
Here's a handy query for finding duplicates in a table.
Initial Title 
Finding duplicates with SQL
Initial Tags 
sql, find
Initial Language 
SQL