Blog Entry Tagging/Keyword Script Troubles

[Shai]

I am trying to code a PHP/MySQL script so I can add tags or keywords to entries on my existing blog.

The general idea is this:

Table1 (journal) contains the blog entries and their IDs (and some other data)
Table2 (entry_tags) contains the IDs (from Table1) of each entry that has at least one tag and the IDs (from Table3) of the tags that go with each entry
Table3 (tags) contains the actual tags and their IDs

I have my script working so that I can add one tag per entry. I don't know how to change it so I can add multiple tags per entry.

The input for this is a form INPUT field and the tags would be listed like this: art, friends, new zealand, vacation

Here is my php code so far.

if (isset ($_POST['submit']))
{
    require_once ('../../mysql_connect.php');

    $query = "INSERT INTO journal (entry_id, date, time, icon, mood, title, entry, perm_lvl) VALUE (0, '$date', '$time', '{$_POST['icon']}', '{$_POST['mood']}', '{$_POST['title']}', '{$_POST['entry']}', {$_POST['perm_lvl']})";
    $result = @mysql_query ($query);
    $entryid = mysql_insert_id();

    if (isset ($_POST['tags']))
    {
        $query = "INSERT INTO tags (tag_id, tag) VALUE (0, '{$_POST['tags']}')";
        $result = @mysql_query ($query);
    } else
    {
        print '<center>Please indicate at least one tag for this entry.</center><br />';
    }

    $query = "INSERT INTO entry_tags (id, entry_id, tag_id) VALUE (0, '$entryid', LAST_INSERT_ID())";

    if (@mysql_query ($query))
    {
        print '<center>The entry has been added.</center><br />';
    } else
    {
        print "<center>Could not add the entry because: <b>" . mysql_error() . "</b>.<br /><br />
        The query was $query.<br /><br />";
    }

    mysql_close(); 

Any help appreciated, thanks!