How to delete duplicates on a MySQL table?

Question

I need to DELETE duplicated rows for specified sid on a MySQL table.

How can I do this with an SQL query?

Answer 1

here is how I usually eliminate duplicates

1. add a temporary column, name it whatever you want(i'll refer as active)
2. group by the fields that you think shouldn't be duplicate and set their active to 1, grouping by will select only one of duplicate values(will not select duplicates)for that columns
3. delete the ones with active zero
4. drop column active
5. optionally(if fits to your purposes), add unique index for those columns to not have duplicates again