sql - 数えてWhereと結合する

Question

お客様

CustomerID Name
4001       John Bob
4002       Joey Markle
4003       Johny Brown
4004       Jessie Black

注文

OrderID    Customer   Status
50001      4001       Paid
50002      4002       Paid
50003      4001       Paid
50004      4003       Paid
50005      4001       Paid
50006      4003       Paid
50007      4004       Unpaid

私はこの結合を試みた

Select c.Customer, COUNT(o.OrderID) as TotalOrders
from Customer c
inner join Orders o
on c.Customer = o.Customer
Where o.Status = 'Paid'
Group by c.Customer

しかし、これが結果です。

Customer  TotalOrders
4001      3
4002      1
4003      2

未払いのお客様は含みません。すべての顧客を含めるにはどうすればよいですか?

Customer  TotalOrders
4001      3
4002      1
4003      2
4004      0

Answer 1

Select c.CustomerId, COUNT(o.OrderID) as TotalOrders
from Customer c
left join Orders o on c.CustomerId = o.Customer and o.[Status] = 'Paid'
Group by c.CustomerId

上記を試してください。