Database Reference
In-Depth Information
When necessary, consult the final table list and read the description for this table, and refer
toanyrelationshipdiagramsthatincorporatethistable.Theanswerstothesequestionswill
be useful to you while you're defining rules for this table and focusing on the table in this
manner prepares you for the next step.
Step 2: Review Each Field and Determine Whether It Requires Any Constraints
Examine the Field Specifications sheet for each field and determine whether you should
apply a constraint to any of its elements. Keep the questions from Step 1 in mind as you
review a given specification sheet, and then pose this question:
Based on how the table is used within the database, is a constraint
necessary for any element within this specification?
If the answer is no, move on to the next field; otherwise, go on to the next step. For ex-
ample, assume you're working with the C
UST
C
OUNTY
field in a CUSTOMERS table and
you have just posed the question about the need for a constraint. (
Figure 11.6
shows the
current Logical Elements category for this field.)
