Chapter 36: Working Directly with the Internal Data Model
36
FIGURE 36.10
You have achieved your goal of showing sales by job title.In Figure 36.9, you see that the lower-right drop-down is named Related Column (Primary). The term primary means
that the internal data model uses this field from the associated table as the primary key.
A primary key is a field that contains only unique non-null values (no duplicates or blanks). Primary key fields are
necessary in the data model to prevent aggregation errors and duplications. Every relationship that you create must
have a field designated as the primary key.
So, the Employees table (in the scenario in Figure 36.9) must have all unique values in the Employee_Number field,
with no blanks or null values. This is the only way that Excel can ensure data integrity when joining multiple tables.
Managing Relationships in the Internal Data Model
After you assign tables to the internal data model, you might need to adjust the relation-
ships between the tables. To make changes to the relationships in an internal data model,
activate the Manage Relationships dialog box.Click the Data tab in the Ribbon and select the Relationships command. The dialog box
shown in Figure 36.11 displays.