How to use GROUP_CONCAT for a column and COUNT(*)? I get the ids of a query by GROUP_CONCAT.
SELECT GROUP_CONCAT(ArticleID) FROM TagMap WHERE Tag IN(...)

How can I merge this query with a COUNT(*) group by
SELECT ArticleID,COUNT(*) FROM TagMap WHERE Tag IN(...) GROUP BY ArticleID

to get GROUP_CONCAT(ArticleID) with order of COUNT(*)?
In other words, in the first query, I want to make GROUP_CONCAT(ArticleID) order by the number of tags found for each ArticleID.
This would helpful, Give a try once
SELECT GROUP_CONCAT(ArticleID)
   ,COUNT(1) AS CNT
FROM (SELECT Tag
         ,ArticleID
         ,COUNT(1) AS CNT
  FROM TagMap Tag IN (...)
  GROUP BY Tag
           ,ArticleID) tmp
  GROUP BY Tag
  ORDER BY cnt