How to find duplicate rows in MySQL database table

I’ve been asked the question “How can I return duplicate rows only from a MySQL db table” many times, so I’ve decided to post a writeup here in a short article. After all, it seems such a common requirement. Any DBA undoubtedly has come across the need to find duplicates in a table.

If you’re really concerned about duplicate rows, or even more profound, if you’re code logic depends on unique entries in a mysql table, you really should implement a ...