Question

I’ve got a database my_table [id,first,second,third] with a lot of entries and want to delete duplicate data of entries [first,second,third].

so that no duplicate for first and no duplicate for second and no duplicate for third
just any duplicate on each then will be deleted.

id   first   second   third
1    addy      any     robert
2    addy     kevin    steve
3    jack      ben     adam

here i will remove duplicate for first so remove 2 addy kevin steve

Answer 1

I would do this in several steps. I would first get a list of all duplicate entries by running the query:

select count(id) "count", first from my_table where count > 1 group by first

This should (theoretically… I can’t test it) return a list of all “firsts” that have duplicates.

Then I would loop through each “first” in the list and run:

delete from my_table where first = "the_first_in _your_loop" and id not in (select min(id) from my_table where first = "the_first_in _your_loop")

That should get you started!