This is because you used a lazy short cut, if you ha full_group_b<Y enabled this would immediately given an error
You have to use aggregation functions for all for all columns that are not in the
SELECT id_forum_cat ,lang ,GROUP_CONCAT(id_forum) id_forum ,GROUP_CONCAT(date_insert) date_insert ,GROUP_CONCAT(question) question ,GROUP_CONCAT(description) description ,GROUP_CONCAT(cat) cat ,SUM(total_replies) , COUNT(*) AS total_topics FROM ( SELECT forum.id_forum_cat AS id_forum_cat, forum.lang AS lang, forum.id_forum AS id_forum, forum.date_insert AS date_insert, forum.question AS question, forum.description AS description, forum_cat.name AS cat, COUNT(forum_reply.id_forum_reply) AS total_replies FROM forum LEFT JOIN forum_reply ON forum_reply.id_forum = forum.id_forum JOIN forum_cat ON forum_cat.id_forum_cat = forum.id_forum_cat GROUP BY id_forum ORDER BY forum.date_insert DESC ) AS tmp_forum GROUP BY lang, id_forum_cat
id_forum_cat lang id_forum date_insert question description cat SUM(total_replies) total_topics 1 en 3,2,1 2020-10-27 18:21:48,2020-10-27 18:13:29,2020-10-27 09:53:26 This is my third question! Right?,This is my second question. Right?,First! How do you say horse in spanish? Im adding a third question for count purposes.,Im adding a second question for count purposes.,This is the first question of the first category. I need how to say horse in spanish in a conversation. general,general,general 3 3 2 en 4 2020-10-27 19:17:01 First question in other category? This is the first question of the second category. grammar 0 1
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