Database Reference
In-Depth Information
Figure 12.11. Revised table diagram; note the new APPROVED
SUBCONTRACTORS view.
The APPROVED SUBCONTRACTORS view now gives users access only to those fields
that you've indicated and provides the appropriate range of values for the S
UBCONTRACTOR
ID field in the PROJECT SUBCONTRACTORS table. Additionally, the view will still en-
force the relationship characteristics that exist forthe SUBCONTRACTORStable because
it (as you will recall) is the view's base table.
Determining and Defining Views
Bynowyou'veprobablyrealizedthatviewscanbeasubstantialassettothedatabase.Dur-
ing this stage of the database design process, you'll define a fundamental set of views for
thedatabase.Yourdefinitionofviewswon'tstophere—you'llprobablydefinemoreviews
when you implement the database within your RDBMS and as you create your end-user
application programs.Intheseinstances, you'lluseviewsasatooltosupportparticular as-
pects of the implementation or application program. The views you define during the data-
base design process, however, will focus strictly on data access and information retrieval
issues.
Working with Users and Management
You'll work once again with the organization's representative group of users and man-
agement to identify the types of views the organization requires. After you identify these
views, you'll establish and document them, and then you and the group will review the
views to make certain that they are properly defined.
Before you conduct your first meeting with the group, review the notes you've taken
throughout the entire design process. Your objective is to get an idea of the types of views
theorganizationmightneed.Almosteveryorganizationspendsalargeamountoftimepro-
