Database Reference
In-Depth Information
Furtherinvestigation ofthefieldsrevealsthatalmostallofthemcomplywiththeElements
of the Ideal Field. The only exceptions are the address fields in the CUSTOMERS and
EMPLOYEEStables,andtheE
MPLOYEE
N
AME
fieldsintheEMPLOYEESandINVOICES
tables. After ascertaining that you can decompose each address field into four individual
items—street address, city, state, and zip code—you transform these items into fields and
add them to the CUSTOMERS and EMPLOYEES tables. Similarly, you notice that the
E
MPLOYEE
N
AME
field represents two items—first name and last name—and you make the
appropriate adjustments to that field in the EMPLOYEES and INVOICES tables.
Figure 7.36
shows the result of all the changes you've made to the fields.
Figure 7.36. Refinements to the fields in the table structures
Your final task is to refine the table structures. Make certain that you have assigned the ap-
propriate fields to each table and that you have properly defined each table. Remember to
follow these steps as you work with each table.
1.
Resolve unnecessary duplicate fields.
When you create new tables as a result of
resolving duplicate fields, make sure you properly identify them and add them to
the Final Table List.
