can't pull info form database that uses PASSWORD() function

I have this user login process page. at this point the user has entered the info and all of this works BUT I cannot figure out how to pull the encrypted password out of the DB. I need to extract with the PASSWORD() function and do not know how. I know this is not the best way to do it but its what the assignment calls for. I have the problem section commented out I think thats what needs fixing.

//sets $query to read usnername and passowd from table
$query = "SELECT username,password,first_name,last_name FROM jubreyLogin WHERE username      
= '$userName' AND password=password('$userPassword')";
$result = mysql_query($query,$db);
if(mysql_error())
{
echo $query;
echo mysql_error();
}

//reads data from table sets as an array
//checks to see if user is already registered
while($row=mysql_fetch_array($result))
{
if($userName == $row['username'] 开发者_如何学运维/*&& $userPassword == ($row['password'])*/)
{
    $login = 'Y';
    $welcome = "Welcome" . " " .$row['first_name']. " " .$row['last_name'];
    $userName = $row['username'];

}
}

if ($login='Y')
{

    setcookie('name',$welcome,time()+60*60*24*30);

    setcookie('login',"Y",time()+60*60*24*30);
    $_SESSION['username_login'] = $userName;
    header('Location: welcome.php');
}

Here is the modified code that I should of posted first I need it to check user entered password in this case $userPassword with the encrypted password if its a match it will send the user into the next page of the site.

You don't need to see the password in clear text ( you can't even if you wanted to). As you are checking the record both on password and username you don't need the check in your if() statement. If there is any row found, that means the username/password combination was succesfful and the user can be deemed as logged in.

Edit: The updated code doesn't really make any difference to the actual logic. The logic stays the same, you query the database with username AND encrypted password, if there is a match that means the user has the right to login, so you proceed with setting the cookies/session data and redirect. Although I do not really see the need for the login cookie and the welcome cookie cause you could simply put in both username, fname and lname in the session. If the session on the following pages contains username that means the user has logged in.

The code can go something like this:

//sets $query to read usnername and passowd from table
$query = "SELECT username,first_name,last_name FROM jubreyLogin WHERE username = '$userName' AND password=password('$userPassword')";
$result = mysql_query($query,$db);
if(mysql_error())
{
    echo $query;
    echo mysql_error();
}

// were any rows returned?
if(mysql_num_rows($result)){
    list($userName, $firstName , $lastName) = mysql_fetch_row($result);
    $welcome = "Welcome" . " " .$firstName. " " .$lastName;

    setcookie('name',$welcome,time()+60*60*24*30);
    setcookie('login',"Y",time()+60*60*24*30);
    $_SESSION['username_login'] = $userName;

    header('Location: welcome.php');
}

You should not be encrypting your passwords, you should be hashing them. Try using a library such as phpass to be on the safe side. What you will need to do is hash the passwords and store the hashed value in the database. When a user logs in, you will hash the password they provide and compare that with the hashed value in the database. If the hashes match, the password provided is correct. If not, you send an error to the user. You never need to be able to obtain the password in plain text in order to validate a user.

Also, make sure that you are either escaping your variables using mysql_real_escape_string() or prepared statements or your script will be vulnerable to SQL injection.