I have a very simple table in my Oracle Database with just 2 columns - username and password. <BR><BR>The username column is the primary key and in my register page I am using the following SQL to insert new rows into the database: <BR><BR>[code language="C#"]<BR>string createUserSQL = "Insert into users(username, password)" +<BR> " values(@username, @password)";<BR><BR>OleDbCommand cmd = new OleDbCommand(createUserSQL, conn);<BR>cmd.Parameters.Add("@username", tbUsername.Text);<BR>cmd.Parameters.Add("@password ", tbPassword.Text);<BR>[/code]<BR><BR>However, I don&#039;t know how to check that there isn&#039;t already a user with that username. Is there a quicker way than querying the table to see if the username returns a row? <BR><BR>Thanks for your help, <BR><BR>Wallace