Combine Multiple Query Results in MySQL (by column)

Question

I have 4 different queries and each of them return individual unique set of Results. I need to combine the Query Results with using a single query.

my sample queries

Answer 1

I assume you want your example to return a single row combining the corresponding entries from all these tables. Try this and tell us if it worked:

select * from users as usr
left outer join (calls as cls 
    inner join calls_users as clsusr 
    on cls.id = clsusr.call_id) 
on usr.id = cls.assigned_user_id 

left outer join (meetings as mtn 
    inner join meetings_users as mtnusr 
    on mtn.id = mtnusr.meeting_id) 
on usr.id = mtn.assigned_user_id 

left outer join tasks as tsk 
on usr.id = tsk.assigned_user_id 

left outer join (notes as nts 
    inner join accounts as acnts 
    on acnts.id=nts.parent_id) 
on usr.id = acnts.assigned_user_id 

where user.id = 'seed_max_id'

Answer 2

The best you can do is a UNION or UNION ALL but this requires them to have the same type and number of columns. For example:

SELECT 'Customer' AS type, id, name FROM customer
UNION ALL
SELECT 'Supplier', id, name FROM supplier
UNION ALL
SELECT 'Employee', id, full_name FROM employee

The column names don't have to match. The aliases from the first part will be used for the rest.

I'll also add that instead of:

select cls.* from (calls as cls inner join calls_users as clsusr on cls.id=clsusr.call_id) inner join users as usr on usr.id=cls.assigned_user_id where cls.assigned_user_id='seed_max_id'

you should remove the unnecessary subquery and just do:

SELECT c.*
FROM calls c
JOIN calls_users cu ONc.id = cu.call_id
WHERE c.assigned_user_id = 'seed_max_id'

There's no need for the extra complexity and the above is eminently more readable.