what's wrong in this code

$link = mysql_pconnect ($DB_SERVER, $DB_LOGIN, $DB_PASSWORD);
$selectStmt = "SELECT * FROM user_profile WHERE userid = 'david'";
if (!($result = mysql_db_query($DB, $selectStmt, $link))){
header("Location:http://$HTTP_HOST/$DOCROOT/error.html");
exit();
}

here is the case, the userid 'David' is NOT
in the table 'user_profile', the program should launch the error.html, and exit().
But it is not.
AHHH....what is wrong in my codes here.
pls help

Hi,

I think that there is a resultset created (even though the userid is not found), but it consists of zero rows.

You can try it with a count of the returned rows:
$link = mysql_pconnect ($DB_SERVER, $DB_LOGIN, $DB_PASSWORD);
$selectStmt = "SELECT * FROM user_profile WHERE userid = 'david'";
$result = mysql_db_query($DB, $selectStmt, $link);
$numRows = mysql_num_rows($result); // counts the number of rows in the resultset
if ($numRows < 1){
header("Location:http://$HTTP_HOST/$DOCROOT/error.html");
exit();
}

Peter