Присоединение к 2 или более запросам sql с использованием внешнего соединения

Question

Я пытаюсь вернуть результаты из инструкции 5 sql, используя «внешнее соединение», я хочу, чтобы stock_id, stock_name и сумма продаж каждый день за последние 5 дней возвращались в виде отдельных столбцов. Как его структурировать?

select s1.sid as sid,s1.sname as sname, sum1,sum2,sum3,sum4,sum5
from
(
 select stock.id as sid, stock.Name as sname, sum(orders.Quantity) as 'sum1' from orders inner join stock on `Stock_id`= stock.id where  orders.Created_at Like '2020-05-16%' group by Stock_id asc
) 
as s1
full outer join
(
select stock.id as sid,stock.Name as sname, sum(orders.Quantity) as 'sum2' from orders inner join stock on `Stock_id`= stock.id where  orders.Created_at Like '2020-05-17%' group by Stock_id asc
)
as s2 on s1.sid=s2.sid 
outer join
(
select stock.id as sid,stock.Name as sname, sum(orders.Quantity) as 'sum3' from orders inner join stock on `Stock_id`= stock.id where  orders.Created_at Like '2020-05-18%' group by Stock_id asc
) as s3 on s1.sid=s3.sid 
outer join
( 
select stock.id as sid,stock.Name as sname,sum(orders.Quantity) as 'sum4' from orders inner join stock on `Stock_id`= stock.id where  orders.Created_at Like '2020-05-19%' group by Stock_id asc
)as s4 on s1.sid=s4.sid 
outer join
(
select stock.id as sid,stock.Name as sname, sum(orders.Quantity) as 'sum5' from orders inner join stock on `Stock_id`= stock.id where  orders.Created_at Like '2020-05-20%' group by Stock_id asc
)as s5 on s1.sid=s5.sid 

Answer 1

Использовать условное агрегирование:

select s.id as sid, s.Name as sname,
       sum(case when date(o.created_at) = '2020-05-16' then o.Quantity end) as sum1,
       sum(case when date(o.created_at) = '2020-05-17' then o.Quantity end) as sum2,
       sum(case when date(o.created_at) = '2020-05-18' then o.Quantity end) as sum3,
       sum(case when date(o.created_at) = '2020-05-19' then o.Quantity end) as sum4,
       sum(case when date(o.created_at) = '2020-05-20' then o.Quantity end) as sum5
from orders o inner join
     stock s
     on o.Stock_id = s.id 
group by s.id;

Это намного проще и не требует join привередливых запросов или подзапросов. Также фиксируется арифметика даты c.