HI.I searched this question inform and I found solution to change column property Unique Index.Now If I try to insert same record cmd.ExecuteNonQuery() gives error that record exist ,but how can use this exception to give user a message that record exist and must enter new one ? I am trying to make some thing like

if(cmd.ExecuteNonQuery() !=true )
{
 MessageBox.Show("User Exists");
}

But I dont know what returns cmd.ExecuteNonQuery() ?

Or I must get records using reader in table and compare them with text in Textfiel?