Checking mysql db for duplicate #s

[Anon]

If I have a user enter, lets say a
CardNumber from a merchant card, into a form that gets posted to an insert mysql script that enters data into a mysql dbase table, how would i check each existing row to see if that cardnumber already exists?

[shastry]

Hi,
Before the INSERT STATEMENT you should check if the CardNumber is alredy exists or not..
Do some thing like this..

$RESULT = mysql_query("SELECT * from TABLE where CardNumber ='$CardNumber'");
$ows = mysql_num_rows($RESULT);
if (!$ows < 1)
{
PRINT "SORRY THIS CardNumber HAS BEEN ALREADY ENTERED!!";
exit();
}
INSERT YOUR INSERT CODE HERE..
Hope this will help..
--Shastry