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

Without using CTE and ROW_NUMBER() you can just delete the records just by using group by with MAX function here is and example

DELETE
FROM MyDuplicateTable
WHERE ID NOT IN
(
SELECT MAX(ID)
FROM MyDuplicateTable
GROUP BY DuplicateColumn1, DuplicateColumn2, DuplicateColumn3)