Question

I have a script that did double inserts into the database with the same data. Is there a good way to do this (without scanning through, inserting every record into an array, and then deleting duplicate array entries)?

Answer 1

MySQL supports multi-table DELETE which is really cool and can help here. You can do a self-join on the equality of all columns except the id, and then delete the matching row with the greater id.

DELETE t2  FROM mytable t1 JOIN mytable t2   USING (column1, column2, column3) -- this is an equi-join WHERE t1.id < t2.id;