从一个表联接计数以从另一个表选择-MySQL

Question

I have a select query with a subquery in it on table a:

select UserName, Name, anniversaryDate, RegionCode 
from a where UserName in
(
    select Username from
    (
        select Username, max(timeUsed)
        from log_table where role='Cou'
        group by Username order by max(timeUsed) desc limit 10
    ) a
)

which works fine, now I have another table called b, on that table I only have 3 columns:

UserName, PName and feedback

which have each UserName multiple times and I want to join to my first query the count of each UserName I got from the first query.

for eaxmple:

SELECT COUNT(UserName) FROM b where UserName='Admin' group by UserName

How do I join the results from the second query to the first one?

Tables:

log_table :
id - Int, AI, PK
Username - varchar
Action - Int
timeUsed - Datetime
role - varchat

a:
UserName - varchar, PK
Name - varchar
anniversaryDate - Datetime
RegionCode - Int

b:
UserName - varchar
PName - varchar
feedback - varchar

Answer 1

Based on your table structure the query below might add the necessary column you are looking for:

    select users.UserName, Name, anniversaryDate, RegionCode, 
        Coalesce(count(b.UserName),0) as cnt 
    from users 
        left outer join (select Username, max(timeUsed)
            from log_table where role='Cou'
            group by Username order by max(timeUsed) desc limit 10
        ) a using (UserName)
        left outer join fedbacks b on (a.UserName = b.userName)
        group by users.UserName;