How to delete duplicate rows in SQL Server?

Question

How can I delete duplicate rows where no unique row id exists?

My table is

col1  col2 col3 col4 col5 col6 col7
john  1          


        

Answer 1

should work equally as in other SQL servers, like Postgres:

DELETE FROM table
WHERE id NOT IN (
   select min(id) from table
   group by col1, col2, col3, col4, col5, col6, col7
)