Checking for duplicate user name

[Anon]

I checked the other messages regarding this topic and thought I had the answer BUT it doesn't seem to work for me and i'm not sure why.

Here's the error I get:
Warning: Supplied argument is not a valid MySQL-Link resource in c:\phpweb/ldscalgary/newmemberacceptance.php on line 69

Warning: Supplied argument is not a valid MySQL result resource in c:\phpweb/ldscalgary/newmemberacceptance.php on line 70

The following are lines 69 and 70 along with the surrounding statement:
$result = mysql_query("SELECT * FROM clients WHERE CUserName LIKE '$CUserName'",$db);
if ($myrow = mysql_fetch_array($result))
{
print "I'm sorry, the user name you selected is currently in use, please select another.<BR>Please press on the back button of your browser.";
exit;
}
else
{
<INSERT STUFF INTO DATABASE>
}

[Anon]

Well for one, if you are comparing the username they entered to one in the database, you can get rid of the LIKE statment, and use:

WHERE CUserName='$CUserName'

Now for the errors, are you sure

and then do:

$count = mysql_num_rows($result);
if ($count >= 1)
{
there are more then 1 user
}
else
{
there are no users
}

hope this helps a bit

[Anon]

Oops, typed that one in spurts. Anyways, the last post was a better method of doing things, but regarding your errors, are you sure you are connecting to the DB?

[Anon]

Yes, it seems to be inserting data fine.