Combining multiple JOINS(inner and Left)into one Select - mysql

Question

My problem is that i have 4 tables, that i want to combine. Table1 has Tickets, Table2 with users, Table 3 with admins and Table4 with files. My Select was woring great when i had only 3 tables, without files, my select back then was something like this
SELECT
Table1.TicketNumber,
Count(Table1.TicketNumber) as "number of tickets",
Table2.UserName,
Table3.AdminName
FROM Table1
inner join
table2 on table1.ID_U=table2.ID
inner join
table3 on table1.ID_A=table3.ID
GROUP BY Table1.TicketNumber
Then i decided to add to my select another table(Table4), from which i would sum number of files for corresponding Ticket, and my Select is something like this:
SELECT
Table1.TicketNumber ,
Table1.count,
Table4.count
FROM
( SELECT TicketNumber,
count(*) AS count
FROM Table1
GROUP BY TicketNumber
)Table1
LEFT JOIN
( SELECT TickerNumber,
count(*) as count
FROM Table2
GROUP BY TicketNumber
) Table2 ON Table1.Name=Table2.Name
My problem is when i try to in somehow merge these two selects to get all that i want, i get syntax error in my INNER JOIN that Table1.ID_U doesnt exist.
Here is simplified struct of my Tables
Table1 Table 2/3
+----+--------------+------+------+----------+ +----+----------------+
| ID | TicketNumber | ID_U | ID_A | SomeData | | ID | User/Admin Name|
+----+--------------+------+------+----------+ +----+----------------+
| 0 | T001 | 1 | 1 | blah | | 0 | Name |
| 1 | T002 | 2 | 3 | blah | | 1 | Name |
| 2 | T002 | 2 | 3 | blah | | 2 | Name |
| 3 | T003 | 2 | 2 | blah | | 3 | Name |
| 4 | T004 | 3 | 1 | blah | | 4 | Name |
+----+--------------+------+------+----------+ +----+----------------+
My Table4
+----+------------+----------+
| ID | TicketName | FileName |
+----+------------+----------+
| 0 | T002 | Name |
| 1 | T002 | Name |
| 2 | T003 | Name |
| 3 | T004 | Name |
| 4 | T007 | Name |
+----+------------+----------+
My goal is to reach Select that looks like this
+----+--------------+----------------+--------------+----------+-----------+
| ID | TicketNumber | HowManyTickets | HowManyFiles | User | Admin |
+----+--------------+----------------+--------------+----------+-----------+
| 0 | T001 | 1 | 0 | UserName | AdminName |
| 1 | T002 | 2 | 2 | UserName | AdminName |
| 2 | T003 | 1 | 1 | UserName | AdminName |
| 3 | T004 | 5 | 1 | UserName | AdminName |
+----+--------------+----------------+--------------+----------+-----------+
Unfortunaly all i am capable of doing is either getting
TicketNumber, HowManyTickets, HowManyFiles,
or
TicketNumber, HowManyTickets, User, Admin

Answer 1

It seems your result ID is generated since its not anymore the same to your TicketID.
Here's my suggestion, using row_number() to generate the ID, then use sum() aggregation function to group your ticketNumber. left join will give you 0 result on your Ticket T001.
select row_number() over (order by t1.TicketNumber) as ID
, t1.TicketNumber
, sum(case when coalesce(t1.TicketNumber, '') = '' then 0 else 1 end) as HowManyTickets
, coalesce(t4.numFiles, 0) as HowManyFiles
, t2.Name as USER
, t3.Name as Admin
from table1 t1
left join table2 t2 on t2.ID = t1.ID_U
left join table3 t3 on t3.ID = t1.ID_A
left join
(select count(1) as numFiles, TicketNumber from table4 group by TicketNumber) t4 on t4.TicketNumber = t1.TicketNumber
group by t1.TicketNumber, t4.numFiles