MySQL - where IN along with GROUP_CONCAT

Question

The query used inside IN () returns: 1, 2 . However, the entire query returns 0 rows, which is not possible since they are present. What am I doing wrong here?

 SELECT DISTINCT li.auto_id FROM links AS li JOIN group_data AS gi ON li.auto_id = gi.autoid AND li.user_id = gi.userid WHERE gi.groupid IN ( SELECT CAST( GROUP_CONCAT( gf.groupid ) AS CHAR ) FROM group_followers AS gf WHERE gf.userid_ext = '1' GROUP BY gf.userid_ext ) AND li.keyword LIKE '%shiba%' 

Thank you very much,

Ice

Answer 1

From documents :

GROUP_CONCAT (expr):
This function returns a string result with non-NULL concatenated values ​​from the group.

You will get a string containing '1,2' . This is something you cannot submit to an IN clause because it is one value, not two.

Just do it without GROUP_CONCAT and it will work:

 gi.groupid IN ( SELECT gf.groupid FROM ... )