Question

I am receiving this mysql error and i don’t know why. I am following a tutorial and i have copied the syntax from the video word for word. Can anybody spot whats wrong?

Here is the error:

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘LEFT JOIN ( SELECT post_id, COUNT(comment_id) AS `total_co’ at line 11

     $query = "SELECT 
        `posts`.`post_id`                 AS `id`,
        `posts`.`post_title`              AS `title`,
         LEFT(`posts`. `post_body`, 512)  AS `preview`,
        `posts`.`post_user`               AS `user`,
         DATE_FORMAT(`posts`.`post_date`, '%d/%m/%Y %H:%i:%s') AS `date`,
         `comments`.`total_comments`,
        DATE_FORMAT(`comments`.`last_comment`, '%d/%m/%Y %H:%i:%s') AS `last_comment`

         FROM `posts`, 
         LEFT JOIN (
            SELECT 
                `post_id`,
                COUNT(`comment_id`) AS `total_comments`,
                MAX(`comment_date`) AS `last_comment`
            FROM `comments`
            GROUP BY `post_id` 
         ) AS `comments`
         ON `posts`.`post_id` = `comments`.`post_id` 
         ORDER BY `posts`.`post_date` DESC";

Your help is much appreciated. Thank you.

Answer 1

Remove the comma , at line 10:

FROM `posts`
     LEFT JOIN 

The correct syntax is:

FROM  
    <table a>
  LEFT JOIN  
    <table b>
      ON  <join condition>

---

Unrelated to the problem:

• For a (small) improvement on efficiency, change the COUNT(comment_id) to:

          COUNT(*) AS total_comments,
  

• You could also add a (post_id, comment_date) index on table comments

• In the main SELECT list, if you prefer to have 0s than NULLs for posts without comments, change comments.total_comments, to:

  COALESCE(comments.total_comments, 0) AS total_comments,