如何连接两个表并按第三个表排序？

Question

So I have three tables, however my SQL JOIN statement continuously returns the same result for some reason instead of returning all rows and ordering them by the third.

This statement correctly works and returns the gName and uName as expected:

SELECT rpg.name AS gName, u.username AS uName FROM roleplay_gangs rpg LEFT JOIN users u on u.id = rpg.owner_id

However when I try to select and order it by a field within the third table, the result isn't as expected for some reason. I've looked around for a while and attempted multiple times but none seem to work for me, never had to join more than 2 tables and order at the same time.

So... I attempted to try it with the third table:

SELECT rpg.name AS gName, u.username AS uName, COUNT(rpgt.gang_id) AS gCount FROM roleplay_gangs rpg LEFT JOIN users u on u.id = rpg.owner_id LEFT JOIN roleplay_gangs_turfs rpgt on rpg.id = rpgt.gang_id ORDER BY gCount

result:

gName | uName | gCount
-----------------------
test  | hello | 2

expected:

gName | uName | gCount
-----------------------
test  | hello | 2
zmaj  | hello | 0
thir  | ajtea | 0

Any help is appreciated, able to post more details on request if required.

Answer 1

The fields you are selecting that you want to be unique in the results should be included in the group by clause when using aggregation such as count :

SELECT
    rpg.name AS gName, 
    u.username AS uName,
    COUNT(rpgt.gang_id) AS gCount
FROM 
    roleplay_gangs rpg
LEFT JOIN
    users u on u.id = rpg.owner_id
LEFT JOIN
    roleplay_gangs_turfs rpgt on rpg.id = rpgt.gang_id
GROUP BY
    rpg.name, 
    u.username 
ORDER BY gCount