Unknown Column in 'field list' php mysql

I've looked everywhere but I cant find an answer for this question. I've seen several solutions that have helped people, but when I try it, I see I'm doing everything right and have nothing to fix. I'm making a forum and i'm trying to insert these into a mysql table but every time I try it says:

Unknown column '6c09e4fe82d47011bf9b25b05946307f' in 'field list'.

The long code is a user id for one of the users, and Its supposed to get inserted, but for some reason its looking for a column with that name. I've only gotten up to the first query with an error so the second part might be totally fine, I don't know.

$sql = "INSERT INTO 
                    topics(topic_subject,
                           topic_date,
                           topic_cat,
                           topic_by)
               VALUES('" . mysql_real_escape_string($_POST['topic_subject']) . "',
                           NOW(),
                           " . mysql_real_escape_string($_POST['topic_cat']) . ",
                           ". $_SESSION['userid'] ."
                           )";

        $result = mysql_query($sql);
        if(!$result)
        {
            //something went wrong, display the error
            echo 'You did everything right, yet there is an error. WEIRD RIGHT???<br /><br />' . mysql_error();
            $sql = "ROLLBACK;";
            $result = mysql_query($sql);
        }
        else
        {
            //the first query worked, now start the second, posts query
            //retrieve the id of the freshly created topic for usage in the posts query
            $topicid = mysql_insert_id();

            $sql = "INSERT INTO
                        posts(post_content,
                              post_date,
                              post_topic,
                              post_by)
                    VALUES
                        ('" . mysql_real_escape_string($_POST['post_content']) . "',
                              NOW(),
                              " . $topicid . ",
                             ". $_SESSION['userid'] ."
                        )";
            $result = mysql_query($sql);