discussion forum from j. meloni's book

The following code is From Julie Meloni's textbook - PHP, mySQL and Apache (SAMS) on page 305-307 / Listing 14.5: It's the last script of a discussion forum which is comprised of four php files and one html file. The script can be seen at: http://www.thickbook.com Chapter 14 off the zipfile. Anyway, in the textbook and the zip her mySQL query reads: ................... $verify = "select ft.topic_id, ft.topic_title from forum_posts as fp left join forum_topics as ft on fp.topic_id = ft.topic_id where fp.post_id = $_GET[post_id]"; ................. The part that I'm confused about is: ............... select ft.topic_id, ft.topic_title from forum_posts ................ It seem that the alias of ft refers to forum_title - not forum_posts. In fact, I switched the query to read as follows: ................ $verify = "select ft.topic_id, ft.topic_title from forum_topics as ft left join forum_posts as fp on fp.topic_id = ft.topic_id where fp.post_id = $_GET[post_id]"; .................. And that seems to run fine. Any explanations will be appreciated. Her original code is below. Thank you. Tony Ritter .......................... <?php //connect to server and select database; we'll need it soon $conn = mysql_connect("localhost", "root", "thisisapassword") or die(mysql_error()); mysql_select_db("sitename",$conn) or die(mysql_error()); //check to see if we're showing the form or adding the post if ($_POST[op] != "addpost") { // showing the form; check for required item in query string if (!$_GET[post_id]) { header("Location: topiclist.php"); exit; } //still have to verify topic and post $verify = "select ft.topic_id, ft.topic_title from forum_topics as ft left join forum_posts as fp on fp.topic_id = ft.topic_id where fp.post_id = $_GET[post_id]"; $verify_res = mysql_query($verify, $conn) or die(mysql_error()); if (mysql_num_rows($verify_res) < 1) { //this post or topic does not exist header("Location: topiclist.php"); exit; } else { //get the topic id and title $topic_id = mysql_result($verify_res,0,'topic_id'); $topic_title = stripslashes(mysql_result($verify_res, 0,'topic_title')); print " <html> <head> <title>Post Your Reply in $topic_title</title> </head> <body> <h1>Post Your Reply in $topic_title</h1> <form method=post action=\"$_SERVER[PHP_SELF]\"> <p><strong>Your E-Mail Address:</strong><br> <input type=\"text\" name=\"post_owner\" size=40 maxlength=150> <P><strong>Post Text:</strong><br> <textarea name=\"post_text\" rows=8 cols=40 wrap=virtual></textarea> <input type=\"hidden\" name=\"op\" value=\"addpost\"> <input type=\"hidden\" name=\"topic_id\" value=\"$topic_id\"> <P><input type=\"submit\" name=\"submit\" value=\"Add Post\"></p> </form> </body> </html>"; } } else if ($_POST[op] == "addpost") { //check for required items from form if ((!$_POST[topic_id]) || (!$_POST[post_text]) || (!$_POST[post_owner])) { header("Location: topiclist.php"); exit; } //add the post $add_post = "insert into forum_posts values ('', '$_POST[topic_id]', '$_POST[post_text]', now(), '$_POST[post_owner]')"; mysql_query($add_post,$conn) or die(mysql_error()); //redirect user to topic header("Location: showtopic.php?topic_id=$topic_id"); exit; } ?>