How to detect duplicate rows in a SQL Server table?

Question

What is the most efficient way to detect duplicates in a 10 column / 50K row table? I\'m using MSSQL 8.0

Answer 1

To detect, just group by as Guge said.

select fieldA, fieldB, count(*) from table
group by fieldA, fieldB
having count(*) > 1

If you want to delete dupes... pseudo....

select distinct into a temp table
truncate original table
select temp table back into original table

With truncate you may run into problems if you have FK constraints, so be smart about dropping constraints and making sure you don't orphan records.