内联两张桌子

Question

I need a little help setting up my query. I'm simply trying to access the amount of people who are in the same 'clan' by joining these two tables together, clan, users. Each users has a column 'clan' which is the same as the table clan's column 'roomOwner' and then I'm trying to get the table clan's information along with the amount of members so it would be like: room, roomOwner, members So basically all I have is this:

SELECT c.*, count(u.clan) AS members FROM clans c inner join users u WHERE c.roomOwner = u.clan ORDER BY members;

It only shows one clan though. Any help please?

Answer 1

Your query has no GROUP BY clause. and I think it's only returning single record right? LEFT JOIN is needed here since there are possibilities that a clan has no member.

SELECT  b.roomOwner, COUNT(a.clan) memberCount
FROM    clan b
        LEFT JOIN users a
            ON a.clan = b.roomOwner
GROUP BY b.roomOwner
ORDER BY memberCount 

Answer 2

You forgot GROUP BY. Do you have some "id" column in "clans" table? Group by that "id"

SELECT c.*, count(u.clan) AS members 
FROM clans c 
inner join users u ON c.roomOwner = u.clan
GROUP BY clans.id

And you need LEFT JOIN there instead of INNER JOIN if you want to see info about all clans, even having 0 users.

Answer 3

也许这会有所帮助：从氏族中选择c。*，count（links.id）作为成员c左加入用户u在c.roomOwner = u，clan按u.clan按成员顺序排序