Title: WordPress database error: [Not unique table/alias
Last modified: May 18, 2017

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# WordPress database error: [Not unique table/alias

 *  Resolved [LFABIO](https://wordpress.org/support/users/lfabio/)
 * (@lfabio)
 * [9 years, 10 months ago](https://wordpress.org/support/topic/wordpress-database-error-not-unique-tablealias/)
 * Hello,
 * I have gotten this error on a website I am working on.
 * >  WordPress database error: [Not unique table/alias: ‘jfr_comments’]
   >  SELECT
   > SQL_CALC_FOUND_ROWS znfr_posts.*, AVG( jfr_commentmeta.meta_value ) as average_rating
   > FROM jfr_posts INNER JOIN jfr_postmeta ON ( znfr_posts.ID = jfr_postmeta.post_id)
   > LEFT JOIN jfr_comments ON(jfr_posts.ID = jfr_comments.comment_post_ID) LEFT
   > JOIN jfr_commentmeta ON(jfr_comments.comment_ID = jfr_commentmeta.comment_id)
   > LEFT OUTER JOIN jfr_comments ON(jfr_posts.ID = jfr_comments.comment_post_ID)
   > LEFT JOIN jfr_commentmeta ON(jfr_comments.comment_ID = jfr_commentmeta.comment_id)
   > WHERE 1=1 AND ( ( jfr_postmeta.meta_key = ‘_visibility’ AND CAST(jfr_postmeta.
   > meta_value AS CHAR) IN (‘visible’,’catalog’) ) ) AND jfr_posts.post_type = ‘
   > product’ AND ((jfr_posts.post_status = ‘publish’)) AND jfr_commentmeta.meta_key
   > = ‘rating’ AND ( jfr_commentmeta.meta_key = ‘rating’ OR jfr_commentmeta.meta_key
   > IS null ) GROUP BY jfr_posts.ID ORDER BY average_rating DESC, jfr_posts.post_date
   > DESC LIMIT 0, 24
 * I really don’t know where to start to solve it.
    Thank you for your help and 
   attention!
 * LFABIO

Viewing 3 replies - 1 through 3 (of 3 total)

 *  Thread Starter [LFABIO](https://wordpress.org/support/users/lfabio/)
 * (@lfabio)
 * [9 years, 10 months ago](https://wordpress.org/support/topic/wordpress-database-error-not-unique-tablealias/#post-7585965)
 * Hello, I did study SQL on Codeschool before I tried some plugins: WP-Optimize,
   Advanced Database Cleaner and even was thinking in start learning about Queries
   to solve this issue, as nobody showed here on WordPress to give any help. :\ 
   Sad.
    Was thinking in uploading WP-DBManager and did uploaded Query-monitor 2.11.4
   Before doing anything else I updated WooCommerce and all the error run out. Funny
   is that I deactivated all plugins and understood the trouble was with WooCommerce,
   but I did not see any article explaining about or showing WooCommerce as a possible
   plugin to be fixed in cases like that, see those words: ‘visible’, ‘catalog’,‘
   product’, ‘publish’. Thanks to me, who is learning in the hard way as many. P.
   S.: I see many people posts are not getting any help. WordPress users must watch
   and help the beginners!!! lfabio
 *  [goldhat](https://wordpress.org/support/users/goldhat/)
 * (@goldhat)
 * [9 years ago](https://wordpress.org/support/topic/wordpress-database-error-not-unique-tablealias/#post-9143289)
 * Long time no replies! Just found this today because I have the same or similar
   error on a project. The cause is implied in the error message, the same table
   is being joined twice. Or the same alias (for the table name) is used twice. 
   It’s hard to read these long sql statements but if you suspect a certain table
   is duplicated, search the statement for it and find out where it’s being used.
   When you find a “double join” or duplicate join, figure out a solution. Can’t
   tell you exactly how to solve it, still researching myself, try this stack overflow:
   [http://stackoverflow.com/questions/4267929/whats-the-best-way-to-join-on-the-same-table-twice](http://stackoverflow.com/questions/4267929/whats-the-best-way-to-join-on-the-same-table-twice)
 * In my own project the reason for the double-join is because we have a system 
   where we’re creating the query in a loop, and it creates an array of joins. In
   some cases, the joins are for the same table. We might be able to fix it with
   using a different alias… still researching.
 * Hope this helps, 9-months later hopefully you solved it already.
 *  Moderator [t-p](https://wordpress.org/support/users/t-p/)
 * (@t-p)
 * [9 years ago](https://wordpress.org/support/topic/wordpress-database-error-not-unique-tablealias/#post-9143352)
 * > 9-months later hopefully you solved it already.
 * [@goldhat](https://wordpress.org/support/users/goldhat/), This thread is not 
   only 9 months old, but [@lfabio](https://wordpress.org/support/users/lfabio/)
   has already marked this thread “resolved”!!
 * If you are looking for topics that could benefit from your help, try looking 
   in [https://wordpress.org/support/view/no-replies](https://wordpress.org/support/view/no-replies)
 * This thread is closed now

Viewing 3 replies - 1 through 3 (of 3 total)

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## Tags

 * [Comments](https://wordpress.org/support/topic-tag/comments/)
 * [database](https://wordpress.org/support/topic-tag/database/)
 * [table-prefix](https://wordpress.org/support/topic-tag/table-prefix/)

 * In: [Fixing WordPress](https://wordpress.org/support/forum/how-to-and-troubleshooting/)
 * 3 replies
 * 3 participants
 * Last reply from: [t-p](https://wordpress.org/support/users/t-p/)
 * Last activity: [9 years ago](https://wordpress.org/support/topic/wordpress-database-error-not-unique-tablealias/#post-9143352)
 * Status: resolved

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