How to delete duplicate rows in SQL Server 2008?

Question

How can I delete duplicate rows in SQL Server 2008?

Answer 1

Assuming you have a primary key called id and other columns are col2 ...coln, and that by "duplicate" rows you mean all rows where all column values except the PK are duplicated

delete from A where id not in
(select min(id) from A
group by col2, col3, ...coln) as x

i.e. group on all non-PK columns