sql - how to delete duplicates from a database table based on a certain field

Question

i have a table that somehow got duplicated. i basically want to delete all records that are duplicates, which is defined by a field in my table called SourceId. There should only be one record for each source ID.

is there any SQL that i can write that will delete every duplicate so i only have one record per Sourceid ?

Answer 1

Assuming you have a column ID that can tie-break the duplicate sourceid's, you can use this. Using min(id) causes it to keep just the min(id) per sourceid batch.

delete from tbl
where id NOT in
(
select  min(id)
from tbl
group by sourceid
)