Database Reference
In-Depth Information
settable.(Recallthatasubsettableandthedatatablefromwhichitwasderivedmustshare
the same primary key. You learned how to define a subset table in Chapter 7 and how to
establish its primary key in Chapter 8 , Keys . ”)
Figure 10.33. Establishing the one-to-one relationship between the STAFF and
FACULTY tables
Figure 10.34 shows a slightly different example of a one-to-one relationship. Assume
that MANAGERS is a subset table of EMPLOYEES but has a direct relationship to
DEPARTMENTS—a single manager is associated with only one department and a single
department is associated with only one manager. Further assume that MANAGERS is the
parent table and DEPARTMENTS is the child table. (This is a good example of a scenario
in which you can choose the roles rather arbitrarily. It's also an instance of when a subset
table plays the parent role within the relationship.)
Figure 10.34. A one-to-one relationship with a subset table in the parent role
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