Joining tables in Tableau - Cell-by-Cell Formula Trace

Sample Data

Two tables: Orders (A1:C4) and Customers (E1:G4). Orders has order details with CustomerID. Customers has customer info with CustomerID.

Cell	Value
A1	OrderID
B1	CustomerID
C1	OrderDate
A2	1001
B2	C01
C2	2024-01-10
A3	1002
B3	C02
C3	2024-01-12
A4	1003
B4	C03
C4	2024-01-15
E1	CustomerID
F1	CustomerName
G1	Country
E2	C01
F2	Alice
G2	USA
E3	C02
F3	Bob
G3	Canada
E4	C04
F4	Diana
G4	UK

Formula Trace

JOIN Orders and Customers ON Orders.CustomerID = Customers.CustomerID (Inner Join)

Step 1: Identify matching CustomerID values in Orders and Customers

Step 2: For each matching CustomerID, combine the row from Orders with the row from Customers

Step 3: Exclude Orders rows with CustomerID not in Customers (like C03)

Step 4: Final joined table columns: OrderID, CustomerID, OrderDate, CustomerName, Country

Cell Reference Map

Orders Table       Customers Table
+-------+---------+------------+   +------------+--------------+---------+
| A1    | B1      | C1         |   | E1         | F1           | G1      |
|OrderID|CustomerID|OrderDate  |   |CustomerID  |CustomerName  |Country  |
+-------+---------+------------+   +------------+--------------+---------+
| A2    | B2      | C2         |   | E2         | F2           | G2      |
|1001   | C01     | 2024-01-10 |   | C01        | Alice        | USA     |
| A3    | B3      | C3         |   | E3         | F3           | G3      |
|1002   | C02     | 2024-01-12 |   | C02        | Bob          | Canada  |
| A4    | B4      | C4         |   | E4         | F4           | G4      |
|1003   | C03     | 2024-01-15 |   | C04        | Diana        | UK      |
+-------+---------+------------+   +------------+--------------+---------+

Arrows: Orders.CustomerID (B2:B4) join to Customers.CustomerID (E2:E4)

Shows the two tables side by side with CustomerID columns highlighted as join keys.

Result

+---------+------------+------------+--------------+---------+
|OrderID  |CustomerID  |OrderDate   |CustomerName  |Country  |
+---------+------------+------------+--------------+---------+
|1001     |C01         |2024-01-10  |Alice         |USA      |
|1002     |C02         |2024-01-12  |Bob           |Canada   |
+---------+------------+------------+--------------+---------+

The joined table shows only orders with matching customers. Order 1003 is excluded because C03 is not in Customers.

Sheet Trace Quiz - 3 Questions

Which CustomerIDs appear in both Orders and Customers tables?

A C01 and C03

B C01 and C02

C C02 and C04

D C03 and C04

Key Result

Joining tables matches rows where key columns are equal and combines their columns into one table.