Precheck database using sql query in asp

Hi,

I have created a registration form. I am saving randomly generated number into sql database everytime you submit a form But What if unfortunately the new generated random number will same as the number already stored in database. To secure the database from the being crashed I want to create a prechecking function or method .That method will first check the database ,if the same record found then regenerate random number everytimes. I want this code in ASP . Can anybody help me out please??..
I was doing something like following:

strSQL = Select * from Table_Name where Random_Number = '"+randomNum+"'

objConn.Open strConn
Set objRS = Server.CreateObject("ADODB.Recordset")
objRS.Open strSQL, objConn



If Not (objRS.EOF And objRS.BOF) Then
objRS.MoveFirst
Do Until objRS.EOF
objRS.MoveNext
Loop

End If



Thank you in advance..