Question

Possible Duplicate:
Remove duplicates using only a MySQL query?

I have a table with different pages but some of them are duplicates. The only way to determine duplicates are by title. I run the code below and it works perfectly:

<?php

mysql_connect("localhost", "root", "root") or die(mysql_error());
mysql_select_db("old") or die(mysql_error());
$result = mysql_query("SELECT pagetitle, COUNT( * ) c
FROM cms_site_content
GROUP BY pagetitle
HAVING c >1") or die(mysql_error());  
while($row = mysql_fetch_array($result)){
    echo $row['id'].'-'.$row['pagetitle'].'<br />';
}

?>

My question is: How can I erase duplicates and keep only one entry. For example if I have an article called “Duplicate Article” and the result is

Duplicate Article: 3

I want to keep only one.

Answer 1

You’ll want to INNER JOIN the table on itself and delete where the pagetitle values are identical but the primary key (I’m using ID as the identifier) is not.

Try:

DELETE c2 FROM `cms_site_content` c1 INNER JOIN
               `cms_site_content` c2
          ON c1.pagetitle = c2.pagetitle AND c1.ID <> c2.ID

Reference: http://dev.mysql.com/doc/refman/5.0/en/join.html