MYSQL Delete all duplicate rows except one

1. If you want to keep the row with the lowest id value:

   DELETE n1 FROM <table> n1, <table> n2 WHERE n1.id > n2.id AND n1.<column>= n2.<column>

2. If you want to keep the row with the highest id value:

   DELETE n1 FROM <table> n1, <table> n2 WHERE n1.id < n2.id AND n1.<column> = n2.<column

https://stackoverflow.com/questions/4685173/delete-all-duplicate-rows-except-for-one-in-mysql