Database Reference
In-Depth Information
3. A subset table contains fields that are related to a particular data table and further
describes the data table's subject in a very specific manner. (You'll learn more
about subset tables later in this chapter.)
4. A validation table contains relatively static data and is a crucial component of data
integrity. ( Chapter 11 , Business Rules ,” provides further details on this type of
table.)
A table description provides a clear definition of the subject represented by the table and
states why the subject is important to the organization. There are certain guidelines that
govern howyoucreate a table description, and you'll learn about them later in this chapter.
There is a final task you have to perform before you transform your Preliminary Table List
into the Final Table List: refining the table names.
Refining the Table Names
Naming a table is a more complex affair than you may realize at the moment. As you
learnedin Chapter3 , Terminology , ”atablerepresentsasinglesubject;therefore,itsname
mustclearlyidentifythesubjectitrepresents.Thefollowingguidelineswillhelpyoucreate
table names that are clear, unambiguous, descriptive, and meaningful. They will also help
ensure that you name your tables in a consistent manner.
Guidelines for Creating Table Names
Create a unique, descriptive name that is meaningful to the entire organization.
Using unique names helps to ensure that each table clearly represents a different
subject and that everyone in the organization will understand what the table repres-
ents. (If you encounter duplicate table names at this point, resolve the problem us-
ing the techniques you learned earlier in this chapter.) Choose names that are de-
scriptive enough to be self-explanatory. “Vehicle Maintenance” is an example of a
good, descriptive name. Defining a unique and descriptive name does take some
work on your part, but it's well worth the effort in the long run.
Create a name that accurately, clearly, and unambiguously identifies the subject of
the table. Vague or ambiguous names usually indicate that the table represents
more than one subject. When you encounter such a name, identify the subjects the
table truly represents and then treat each subject as a separate table. “Dates” is a
good example of a vague table name. You really don't know what the table repres-
ents without referring to its description. For example, assume you're designing a
database for an entertainment agency and this table appears in the Preliminary
Table List. Upon seeing this table name, you decide to review your interview
notes. You discover that one person says “Dates” represents appointments for cli-
ent meetings, and another person says it represents booking dates for the agency's
Search WWH ::




Custom Search