Cross-database joins in Tableau - Cell-by-Cell Formula Trace

Sample Data

Two tables from different databases: Orders (A1:C4) and Customers (E1:G4). Orders has order details, Customers has customer info.

Cell	Value
A1	OrderID
B1	CustomerID
C1	OrderAmount
A2	1001
B2	C001
C2	250
A3	1002
B3	C002
C3	450
A4	1003
B4	C003
C4	300
E1	CustomerID
F1	CustomerName
G1	Region
E2	C001
F2	Alice
G2	North
E3	C002
F3	Bob
G3	South
E4	C004
F4	Charlie
G4	East

Formula Trace

JOIN Orders.CustomerID = Customers.CustomerID

Step 1: Match Orders.CustomerID 'C001' with Customers.CustomerID

Step 2: Match Orders.CustomerID 'C002' with Customers.CustomerID

Step 3: Match Orders.CustomerID 'C003' with Customers.CustomerID

Step 4: Combine matched rows from Orders and Customers

Cell Reference Map

Orders Table       Customers Table
+-------+---------+------------+   +------------+--------------+--------+
|  A1   |   B1    |    C1      |   |    E1      |     F1       |   G1   |
|OrderID|CustomerID|OrderAmount|   |CustomerID  | CustomerName | Region |
+-------+---------+------------+   +------------+--------------+--------+
| 1001  |  C001   |    250     |   |   C001     |    Alice     | North  |
| 1002  |  C002   |    450     |   |   C002     |    Bob       | South  |
| 1003  |  C003   |    300     |   |   C004     |    Charlie   | East   |
+-------+---------+------------+   +------------+--------------+--------+

Arrows: Orders.CustomerID --> Customers.CustomerID

The join uses CustomerID from Orders (column B) and Customers (column E) to match rows across two different databases.

Result

+---------+------------+--------------+--------+
|OrderID  |OrderAmount |CustomerName  | Region |
+---------+------------+--------------+--------+
| 1001    | 250        | Alice        | North  |
| 1002    | 450        | Bob          | South  |
+---------+------------+--------------+--------+

Result of cross-database join showing orders with matching customer info. Order 1003 excluded because no matching customer.

Sheet Trace Quiz - 3 Questions

Which CustomerID from Orders does NOT find a match in Customers?

A C002

B C003

C C001

D C004

Key Result

Cross-database join matches key columns from two tables in different databases to combine related rows.