mysql如何显示每个用户的最高分

Question

Suppose I have a database with two tables. A "user" table containing an ID, first name, and last name. And a "game" table containing an ID, score, and a userID (the same ID from the user table).

-------------------------              ------------------------
ID | fName | lName                     ID | score | userID
-------------------------              ------------------------
1  |  Joe  | Smith                     1  |   20  |    2
2  |  Jane | Doe                       2  |   15  |    2
3  |  Sam  | Mills                     3  |   18  |    3
--------------------------          4  |   22  |    3

I want to get ONLY the highest score of each user that has played the game. I want to display something like this:

                      Jane |  Doe  | 20
                      Sam  | Mills | 22

Using mysql, how can I achieve this? Also do I need to take into account that there are no records for Joe Smith (userID = 1) in the "game" table?

Thank You to whoever can help!

Answer 1

You can use aggregation and join :

select u.fname, u.lname, gu.max_score
from (select userid, max(score) as max_score
      from games g               
      group by userid
     ) gu join
     users u
     on u.id = gu.userid

Answer 2

For achieve this you can use aggregation function and left join:

SELECT U.id, U.fname, U.lname,IFNULL(MAX(G.score),0) AS score FROM user AS U
LEFT JOIN game AS G ON G.userID = U.id
GROUP BY U.id, U.fname, U.lname

I have used left join so if game table don't have any user record so it would be returning 0.

This is DB FIDDLE link you can check same Qry there.