Database Reference
In-Depth Information
14. Bad Design—What Not to Do
Mistakes are always initial.
—C
ESARE
P
AVESE
Topics Covered in This Chapter
You may have wondered why this chapter appears at the end of the topic instead of at the
beginning. The reason is simple: You can appreciate the dangers presented by a poorly de-
signed database now that you've learned how to design a database properly. Additionally,
you will be able to determine for yourself why a particular design is bad—you'll look at the
designandbeabletoidentifytheproblemswiththestructureimmediately.Youalsopossess
the knowledge required to identify possible solutions to these problems.
Inthischapter,you'llseethe
three most common
designapproachesthatleadtopoorlystruc-
tured databases. The discussions are brief because they are only meant to illustrate types of
design you should avoid. It should now be obvious that the way to resolve an improperly
designed database is to take it through the complete design process you've just learned.
Flat-File Design
Thistypeofdesign(sometimesknownasthe“throw-everything-into-one-big-table” design)
has been in existence for many years and is common in databases that have been designed
for implementation in nonrelational database management systems. A flat-file design is
fraught with problems, as you can see by examining the structure in
Figure 14.1
.
