Databases Reference
In-Depth Information
If we let QlikView make the default associations, we would get the following
data model:
From the preceding image, we can observe that a synthetic key has been created
because two fields (
Employee ID
and
Department ID
) are shared between the
Operations
table and the
Payroll
table.
To solve this challenge, we will remove the synthetic key by using a link table.
As was mentioned earlier, the new link table will hold all combinations of the
key fields that are common for both tables. We should also create a new
compound key to connect the three tables.
Essentially, the link table replaces the synthetic key table, and in some cases, the
result in both performance and design is exactly the same. However, it's a good
practice to always "clean" the data model and remove all synthetic keys.
