MS Access: 'Outer Join' returns unexpected results when querying multiple related tables
I'm writing unit tests and I'm testing a new approach and I'm integrating two systems and I'm working on a project in MS Access 2016 where I need to generate a report that combines data from three related tables using an outer join. However, I'm getting unexpected results where some records seem to be omitted. I've set up the tables as follows: - **Customers** (CustomerID, CustomerName) - **Orders** (OrderID, CustomerID, OrderDate) - **OrderDetails** (DetailID, OrderID, ProductID, Quantity) The relationship between these tables is: - `Customers` to `Orders` is one-to-many (one customer can have many orders) - `Orders` to `OrderDetails` is one-to-many (one order can have many details) Here's the SQL query I used to pull the data: ```sql SELECT Customers.CustomerID, Customers.CustomerName, Orders.OrderID, OrderDetails.ProductID, OrderDetails.Quantity FROM Customers LEFT JOIN Orders ON Customers.CustomerID = Orders.CustomerID LEFT JOIN OrderDetails ON Orders.OrderID = OrderDetails.OrderID; ``` When I run this query, I expect to see all customers, including those without orders or order details. Instead, some customers are being returned with `NULL` values for `OrderID`, `ProductID`, and `Quantity`, which is what I expect, but I'm also missing some customers entirely who should show up as having no related orders or order details. I've double-checked the relationships in the Relationships window, and they seem correct, with referential integrity enforced. I also tried switching the joins from `LEFT JOIN` to `RIGHT JOIN` and the results didn't change. To troubleshoot, I ran a simple query just on the `Customers` table and confirmed that all records are there, so I know this isn't an issue with missing customer data. Is there something I'm overlooking with how the joins are configured, or is there a known peculiarity with MS Access's handling of outer joins when multiple tables are involved? Any insights would be greatly appreciated. Has anyone else encountered this? Thanks for your help in advance! What would be the recommended way to handle this?