MySQL在“复杂” SQL查询中计数

Question

I have the following SQL query: Let me describe it to you quickly. I wanna develop a soccer tip game. I have 4 tables: apps, tips, users, games.

Relations:

apps 1 to N users
user 1 to N tips
game 1 to 1 tip

Instead of listing all games where the User had a successful tip, I just want to list the u.userId with the COUNT of successful tips. Check out my SQL:

SELECT 
    t.*, u.*, g.*
FROM 
    tips AS t,
    users AS u, 
    games AS g
WHERE 
    u.userAppId = 4 AND
    t.tipUserId = u.userId AND
    g.gameResult = t.tipGameResult

I guess I somehow have to implement a COUNT and u.userId instead of

 t.*, u.*, g.*

but I am not 100% sure how to do it. Do you have any suggestions?

Answer 1

SELECT 
u.userid, count(*)
FROM 
tips AS t,
users AS u, 
games AS g
WHERE 
u.userAppId = 4 AND
t.tipUserId = u.userId AND
g.gameResult = t.tipGameResult
group by u.userid

As mentioned in comment below, the group by on user id will give you

userid|count(*)