To find duplicate values you need to use the MySQL COUNT() function and then pick out all of the counts that are greater than one.
1) ORDER BY Count DESC;
Conversely you can also select the rows that only have a single entry.
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<p>However, it is very nice to pick out the duplicate entries in a table, but you might still need to do something with them. Here is a query to delete any duplicate rows from a table. It does a simple self join and deletes the row value with the lowest ID.</p> <pre language="sql}DELETE bad_rows.* FROM tests AS good_rows INNER JOIN tests AS bad_rows ON bad_rows.number = good_rows.number AND bad_rows.id > good_rows.id;
More information on this deletion query and other methods of deleting duplicates can be found at Xaprb.com.