okkishore wrote: how we will recover from database was lost or scatch Huh? What kind of stupid interview question was that? Without backing up the database, losing it or having the disc being scratched is pretty much a nail in the coffin for the database, unless you have very pricey hardware to pull data bits off hard disk platters. "The clue train passed his station without stopping." - John Simmons / outlaw programmer

Ok well, if you don't have any unique key you should create one. Add a new column that is an identity. Then if you really don't which record you keep you can do a delete statement like this: delete from yourTable yt join (Select max(id),col1, col2, col3, col4, col5 from yourTable group by col1, col2, col3, col4, col5 having count(*) > 1) temp on yt.id = temp.id Ben