Question

TSQL query to select all records from Customer that has an Order and also select all records from customer that does not have an Order. The table Customer contains a primary key of CustomerID. The table Order contains a primary key of OrderID and a foreign key of CustomerID.

Answer 1

I came up with this solutions.

Select CustomerName
from Customer
Where pk_CustomerID IN
(
Select fk_CustomerID from Orders
INNER JOIN Customer
on Customer.pk_CustomerID=Orders.fk_CustomerID)

/* NOT IN instead of IN will give the other customers who doesn t have an Order */

Answer 2

Something like

Select yourcustomerfields, yourorderfields
From Customer
Left join Orders on Customer.OrderID = Orders.OrderID

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