Database Reference
In-Depth Information
Step 5 - Obtain Higher Order Normalized Relations
There are no MVDs or JDs, therefore relations R2 , R3 , R5 , R6 and R7 are in 4NF and 5NF.
Note:
1.
This is a rather trivial example; a college database is a much
more complex system than the representation presented
here. Moreover, questions may be raised as to the veracity
of some of the FDs stated (for instance FD5). However, the
representation succeeds in providing the application of the
normalization theory, and that was the sole intent.
2.
Relation R6 fulfills FD4 ([H,S] → R), and R7 fulfills FD2
([H, T] → R). Strictly speaking, R7 may be considered
redundant, since we can determine what teacher is in a room
at a given time by accessing R5 and R2 .
5.10 Database Model and Design Tools
At this point you must be wondering, how in the world are you supposed to model and
design a complex database, and keep track of all the entities and relationships? The good
news is, there are various tools that are readily available, so there's no need to panic. The
standard general purpose word processors (such as MS Office, Word Perfect, Open Office,
etc.) are all fortified with graphics capabilities so that if you spend a little time with any
of these products, you will figure out how to design fairly impressive database model/
design diagrams. Better yet, there is a wide range of CASE tools and/or modeling tools
that you can use. Figure 5-18 provides an alphabetic list of some of the commonly used
products. While some of the products in the list are quite impressive, the list is by no
means comprehensive, so you do not have to be constrained by it. Some of the products
are available free of charge; for others, the parent company offers free evaluation copies.
 
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