Database Reference
In-Depth Information
its value. You list calculated fields separately because you'll use them in a specific manner
later in the design process.
You build the Calculated Field List using existing fields from the Preliminary Field List.
Examine the list and determine whether there are fields that fit the description of a calcu-
lated field. Fields that have names containing words such as amount, total, sum, average,
minimum, maximum, and count are likely candidates for the Calculated Field List. Com-
mon names for calculated fields include “Subtotal,” “Average Age,” “Discount Amount,”
and “Customer Count.” As you identify each calculated field, remove it from the Prelim-
inary Field List and place it in the Calculated Field List. When you've completed your ex-
amination of all of the fields in the Preliminary Field List, you'll have two completely new
lists: a third version of the Preliminary Field List and a Calculated Field List.
Reviewing Both Lists with Users and Management
Conduct brief interviews with users and management to review the items that appear on
the Preliminary Field List and the Calculated Field List. Your objective here is to determ-
ine whether there are fields that have been omitted from either list. You can continue with
the next step in the design process when everyone is satisfied that the lists are complete;
otherwise,identifythefieldsthataremissingandaddthemtotheappropriatelist.Oncethe
interviews are complete, you'll have a “final” version of each list.
Be sure youconduct these interviews because the participants' feedback provides youwith
a means of verifying the fields on both lists. Let me remind you once again to avoid be-
coming too invested in the idea that these lists are absolutely complete and final. At this
point you still may not have identified every field that needs to be included in the data-
base—inadvertently, you're almost sure to miss a few fields—but if you strive to make
your lists as complete as you can, the inevitable additions or deletions will be quick and
easy to make.
Case Study
You've already defined the mission statement and mission objectives for Mike's new data-
base. Now it's time to perform an analysis, conduct interviews, and compile a Preliminary
Field List.
First, analyze Mike's current database. As you already know, he keeps most of his data on
paper; the only exception is the product inventory he maintains in a spreadsheet program.
Gather samples of the various papers Mike uses to collect data and a screenshot or printout
of the spreadsheet he uses to maintain the product inventory. Assemble these samples to-
gether inafolder forlater use.Forexample, Figure 6.18 showsasample ofthe index cards
Mike uses to collect customer information, along with a screenshot of his spreadsheet pro-
gram.
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