Beginning Microsoft SQL Server 2008 ... - S3 Tech Training

Chapter 8: Being Normal: Normalization and Other Basic Design Issues
we looked at in the previous section — the Relationships dialog for the SalesOrderHeader table is
shown in Figure 8-18.
Figure 8-18
From here, we can edit the nature of our relationship, including such things as cascading actions, whether
the foreign key is enabled or disabled (for example, if we want to deliberately add data in that violates
the relationship), and even the name of the relationship.
Database designers seem to vary widely in their opinion regarding names for relationships. Some don’t
care what they are named, but I prefer to use a verb phrase to describe my relationships — for example,
in our Customers/Orders relationship, I would probably name it CustomerHasOrders or something of
that ilk. It’s nothing critical — most of the time you won’t even use it — but I find that it can be really
helpful when I’m looking at a long object list or a particularly complex ER Diagram where the lines may
run across the page past several unrelated entities.
Adding Relationships in the Diagramming Tool
Just drag and drop — it’s that easy. The only trick is making sure that you start and end your drag in the
places you meant to. If in doubt, select the column(s) you’re interested in before starting your drag.
Try It Out Adding a Relationship
Let’s add a relationship between our new CustomerNotes table (we created it in the last section) and the
Customers table — after all, if it’s a customer note we probably want to make sure that we are taking notes
on a valid customer. To do this, click and hold in the gray area to the left of the CustomerID column
in the Customers table, then drag your mouse until it is pointing at the CustomerID column in the
CustomerNotes table. A dialog box should pop up to confirm the column mapping between the related
tables (see Figure 8-19).
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