Question

How can I check if value is in mysql’s table’s column?

Right now I’m creating a login system. After the user registers my php file posts the value and makes it into a variable. I was wondering what code i can use to compare my value to those values in the table and to check whether or not there is a value identical to the value entered.

I tried this code.

$query = "SELECT * FROM users WHERE username ='$username';";

$res = mysql_num_rows(mysql_query($query));

and then if ($res >= 0);

but then i get this error,

Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home/synameg1/public_html/giveaway/appfiles/register.php on line 23

so i was wondering if there is either a way to fix this error or do what i want to do in another method.

Thanks!

Answer 1

$sql = "SELECT * FROM users WHERE username = '" . mysql_real_escape_string($username) . "'";
$result = mysql_query($sql) or die("Error occurred in [$sql]: " . mysql_error());
$count = mysql_num_rows($result);