mysql GROUP_CONCAT DISTINCT multiple columns

Question

I have a tag field for a blog posts. tags have unique id but their displayName might be duplicated. What I want is a query that selects posts and in all_tags field we get couples of (id,displayName) is this way:

id1,name1;id2,name2;id3,name3 

My query looks like:

select .... CONCAT_WS(';', DISTINCT (CONCAT_WS(',',tags.id,tags.displayName))) AS all_tags Join ...post content ... Join ...post_tags ... Join ...tags ... ORDER BY posts.id 

This line causes problem:

CONCAT_WS(';', DISTINCT (CONCAT_WS(',',tags.id,tags.displayName))) AS all_tags 

How should I modify it?

Some people use an inner (SELECT .. FROM) but as I have heard, it is so inefficien

---

SELECT `posts`.*,`categories`.*,`creators`.*,`editors`.* CONCAT_WS(';', DISTINCT GROUP_CONCAT(CONCAT_WS(',',tags.id,tags.displayName))) AS all_ids FROM (`posts`)  LEFT JOIN `languages` ON `posts`.`language_id`=`languages`.`id`  LEFT JOIN `users` as creators ON `posts`.`creatorUser_id`=`creators`.`id`  LEFT JOIN `users` as editors ON `posts`.`lastEditorUser_id`=`editors`.`id`  LEFT JOIN `userProfiles` as editors_profile ON `editors`.`profile_id`=`editors_profile`.`id`  LEFT JOIN `categories` ON `posts`.`category_id`=`categories`.`id`  LEFT JOIN `postTags` ON `postTags`.`post_id`=`posts`.`id`  LEFT JOIN `tags` ON `postTags`.`tag_id`=`tags`.`id`  LEFT JOIN `postTags` as `nodetag_checks` ON `nodetag_checks`.`post_id`=`posts`.`id`  LEFT JOIN `tags` as `tag_checks` ON `nodetag_checks`.`tag_id`=`tag_checks`.`id`  WHERE ( 9 IN(`tag_checks`.`id`,`tag_checks`.`cached_parents`) OR 10 IN(`tag_checks`.`id`,`tag_checks`.`cached_parents`) OR 11 IN(`tag_checks`.`id`,`tag_checks`.`cached_parents`))  GROUP BY `posts`.`id` ORDER BY `posts`.`created` desc LIMIT 0, 20   

Answer 1

Try this:

GROUP_CONCAT(   DISTINCT CONCAT(tags.id,',',tags.displayName)    ORDER BY posts.id    SEPARATOR ';' )