if statement

[Confusion]

I'm using this to insert songs that are submitted to my site:

    $insert_song = @mysql_query("SELECT artist_id, artist_name FROM artist ORDER BY artist_name ASC");
    if(!@mysql_num_rows($insert_song))
    {
        die('You have to add at least one artist to the database first');
    }
    else
    {
        if($_POST['submit'] && strlen(trim($_POST['song_name'])))
        {
            $insert = mysql_query("INSERT INTO song SET
                                        artist_id         = '" . $artist_id . "',
                                        song_name         = '" . addSlashes($_POST['song_name']) . "',
                                        song_features    = '" . addSlashes($_POST['features']) . "',
                                        song_lyrics         = '" . addSlashes($_POST['song_lyrics']) . "',
                                        song_contributer = '" . addSlashes($_POST['contributer']) . "',
                                        song_status = 'inactive',
                                        song_modified = NOW(),
                                        song_dateadded = NOW(),
                                        user_id = " . $_SESSION['user_id'] . "
                                ");
             $sql = ("INSERT INTO hits SET
            song_hits=0, artist_id='" . $_POST['artist'] . "', song_id=" . mysql_insert_id() . ", song_hits_dateadded=now()");
            if (@mysql_query($sql)) {
            echo '';
            } else {
            echo '<p>Error submitting default hit value: ' .
            mysql_error() . '</p>';
   }
            if($insert)
            {
                $submit = true;
            }
            else
            {
                die(mysql_error());
            }
        }
    } 

The code works fine for users that have accounts but I get a white screen when guests attempt to submit songs.

This is obviously happening because of this line:

user_id = " . $_SESSION['user_id'] . " 

Is there a way to write an if statement so that if a guest submits a song, the user_id will be blank?

Thank you.

[Jelena]

Build your query this way..

$sql = "INSERT INTO song SET ";
$sql .= " artist_id = '".$artist_id."'";
$sql .= ", song_name = '".addSlashes($_POST['song_name'])."'";
$sql .= ",  song_features = '".addSlashes($_POST['features'])."'";
//etc...
if(isset($_SESSION["user_id"]))
    $sql .= ", user_id = '".$_SESSION["user_id"]."'";
else
    $sql .= ", user_id = ''";
    
$insert = mysql_query($sql); 

PS. It is highly recommended that you check if query failed..

if (!$insert) {
   die('Invalid query: ' . mysql_error());
} 

[betrollwin.com]

use the isset function

darn beat me to it.