mysql 加入子查询问题

Question

I have issue combining sql join with group & subquery to select max value.

table1

user_id user_name
1   x
2   t
3   y
4   i
5   o

table2

user_id game_id
1   soccer
2   soccer
2   pool
2   basketball
5   swimming

table3

user_id fans    date
1   54805   2018-10-05
2   10005   2018-10-05
2   10023   2018-10-03
3   175 2018-10-05
4   1542    2018-10-05

When running this query, which is grouping all game_ids by user_ids I've a success:

SELECT table1.user_id, table1.user_name, group_concat(table2.game_id) as games
FROM (table1
LEFT JOIN table2 on table2.user_id = table1.user_id) 
group by table1.user_id

But when trying to combine subquery to return the latest fans' number:

SELECT table1.user_id, table1.user_name, group_concat(table2.game_id) as games, table3.fans 
FROM ((table1
LEFT JOIN table2 on table2.user_id = table1.user_id) 
INNER JOIN (SELECT * FROM table3 WHERE MAX(update_time) ORDER BY update_time LIMIT 1) AS fans ON table1.user_id = table3.user_id) 
group by table1.user_id

I'm facing issue with the group function:

#1111 - Invalid use of group function

Edit:

Fixed the issue #1111 by changing WHERE to HAVING but my query is still no good as MYSQL report the following:

Unknown column 'table3.fans' in 'field list'

Answer 1

If you use aggregation function you must declare in group by clause all the columns not involved in aggregation function.

You are using an aggregation function MAX(update_time) in where clause and this raise the error invalid use of group function .

the use of an aggregated function in where is not allowed eventually you could filter this result using having clause ..

 SELECT table1.user_id
    , table1.user_name
    , group_concat(table2.game_id) as games
    , fans.my_res 
FROM table1
INNER JOIN (
    SELECT user_id, MAX(update_time)  my_res FROM table3 
    group by user_id
    ORDER BY  my_res DESC LIMIT 1
) AS fans ON table1.user_id = fans.user_id 
LEFT JOIN table2 on table2.user_id = table1.user_id 
group by table1.user_id,  table1.user_name, fans.my_res 

in you case you are also referring to a table3 that is in subquery and is not visibile outside .. so you should refer to this columns using the alias that you have used for the table result of the subquery (fans)