hye all..
now i'm doing an insert statement in asp.net using c#..
how i can make a validation for same data entry?
anyones can help me?

thanks in asdvance...

so, in back in code no need to write anything?

Correct, insert that validator in ASP.NET page and connect it with control. Find more informations about it on the link I gave you. I don't have too much expirience with validators.