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Snippet Name: Find Duplicates

Description: Finds duplicate rows. Also shows code to find a row that occurs only once.

Comment: (none)

Language: MYSQL
Highlight Mode: MYSQL
Last Modified: February 26th, 2009

SELECT email, 
 COUNT(email) AS NumOccurrences
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 )

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