DB Help "UserName Taken" Help

[Mark]

okay, i know you guys dont like giving direct answers, but i've tried this a couple of different ways and i just cant get it to work.. can some one please help? i would like to check my database for a user name to see if it already exists and if it does return some message like "already taken".

heres my script as is.:

<? 
$db = mysql_connect("localhost","****","****");
mysql_select_db ("biohazard_login"); 
if(empty($username) || empty($passwd) || empty($firstname) || empty($lastname) || empty($email))
{
mysql_close($db); 
die();
}

$result = mysql_query ("INSERT INTO biohazard_users (username, passwd, firstname, lastname, email, age, homepage, imservicename, aim, yahoo, icq) 
                VALUES ('$username', '$passwd', '$firstname', '$lastname', '$email', '$age', '$homepage', '$imservicename', '$aim', '$yahoo', '$icq')");

if(!$result) 
{ 
   echo "<b>There was a problem!</b> ", mysql_error(); 
   exit(); 
}
if($result) 
    { 
    mysql_close($db); 
    print "Thank you for registering with Biohazard! you may now login!";
    include("login.php"); 
    } 
?>

[schmalenegger]

Hello Mark,

In your Script, there is only a command for inserting the variables to your database. If you want to look, if a username already exists in your database before inserting, you have to make something like this:

$result = mysql_query ("select user from your_table where user = '$user'");
if (mysql_num_rows($result) != 0)
{
echo "This User already exists";
}
else
{
//insert the whole stuff into your database
}

I hope, this helps you.

[Mark]

Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in C:\Documents and Settings\Mark\Desktop\My Web Sites\biohazard\reg_submit.php on line 167

$check = mysql_query ("select username from biohazard_users where user = '$username'"); 
if (mysql_num_rows($check) != 0)          // Line #167
{ 
echo "Sorry, the UserName $username already exists, please try again."; 
} 
else 
{ 
if($result) 
    { 
    mysql_close($db); 
    print "Thank you for registering with Biohazard! you may now login!";
	include("login.php"); 
    }
} 

[schmalenegger]

hi,

if there is a non valid mysql-result, then it might be, that you have entered a tablename which does not exists or perhaps you haven't connected to your database or havent' chosen the right table!

the script has to be ok, because its form the php.net page:

http://de.php.net/manual/en/function.mysql-num-rows.php

and it works fine at my side.