-- 1st way SELECT * FROM TABLE WHERE FIND_IN_SET(" '.$tag.'", CONCAT(" ", TABLE.tags)) LIMIT 1; -- 2st way SELECT * FROM TABLE WHERE '.$tag.' IN(TABLE.tags) LIMIT 1; -- source: http://www.apphp.com/index.php?snippet=mysql-search-in-tags-set
Lets say you have a table with field called "tags" that consists from tags separated by commas and you want to check whether it includes a required tag. Here the simplest ways of doing that.