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