Finding duplicate values in MySQL

mysql
Jon Tackabury picture Jon Tackabury · Mar 27, 2009 · Viewed 648.4k times · Source

I have a table with a varchar column, and I would like to find all the records that have duplicate values in this column. What is the best query I can use to find the duplicates?

Answer

levik picture levik · Mar 27, 2009

Do a SELECT with a GROUP BY clause. Let's say name is the column you want to find duplicates in:

SELECT name, COUNT(*) c FROM table GROUP BY name HAVING c > 1;

This will return a result with the name value in the first column, and a count of how many times that value appears in the second.

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