Database Reference
In-Depth Information
Why Field Specifications Are Important
Despitewhatyoumayhaveheard,thetimeittakestoestablishfieldspecificationsforeach
field in the database is an investment toward building consistent data and quality inform-
ation—you are not wasting time whatsoever by performing this process. In fact, you'll
waste more time in the end if you only partially perform this process or neglect it entirely.
Shirking this duty means you're bound to encounter (and suffer from) inconsistent and er-
roneous data and inaccurate information.
There are several reasons why field specifications are crucial.
Field specifications help establish and enforce field-level integrity. Implementing
these specifications enables you to guarantee that the data in each field is consist-
ent and valid.
Defining field specifications for each field enhances overall data integrity. Re-
member that field-level integrity is one of the four components of overall data in-
tegrity. Field-level integrity enhances (to some extent) the table-level integrity you
established in the previous stage of the design process. (This will become apparent
when you work with the logical elements of the field specification.)
Defining field specifications compels you to acquire a complete understanding of
the nature and purpose of the data in the database. Understanding the data means
that you can judge whether the data is truly necessary and important to the organiz-
ation, and you can learn how to use it to your best advantage.
Field specifications constitute the “data dictionary” of the database. Each field
specification stores data on the characteristics of a particular field within the data-
base. The complete set of specifications you establish for all of the fields in the
database composes a literal dictionary of the database's structure. This data dic-
tionary is particularly useful when you implement your database in an
RDBMS—you can use it as a guide for creating the fields and setting their funda-
mental properties. These specifications will also help you determine what type of
data entry and data validation procedures you need to implement within any user
interface application you create for the database.
Keepinmindthatthelevelsofconsistency,quality,andaccuracyofthedatainthedatabase
(and information retrieved from that data) are in direct proportion to the degree to which
you complete these specifications. It is paramount that you establish each field specifica-
tion completely if your organization depends heavily on the information you retrieve from
the database.
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