HP Integrity NonStop J-Series - Manual (Page 58)

DEVELOPING A DATA BASE
Drawing the Relationship Between Classes of Information
Sample Data for Dependents
empnum
0001
0001
0001
0002
0004
0004
0004
•••
dependent-name
Jane Jones
Bill Jones
Mark Jones
Judy Martin
Leslie Monte
David Monte
Sue Monte
•••
relationship
S
C
C
C
S
C
C
•••
dependent-age
•••
33
12
10
17
27
3
2
Figure 3-6. Dependents Class with Repeating Data Removed
Although normalization requires you to include the same data item
("empnum") with several occurrences of the dependent data, this
process simplifies your data base files and results in a data
base that can be handled by both ENABLE and ENFORM.
Drawing the New Relationship
After you remove any data items that are associated with more
than one class of data and eliminate repeating data from each
class, you can draw a new diagram that shows the relationship
between the classes. Since the repeating information has been
removed from the dependents class, each employee occurrence is
now related to several dependents occurrences. Figure 3-7
illustrates this new relationship.
3-7