Data Normalization - Information Systems Reengineering, Integration and Normalization - page 365

Teaching

idref
0

* *

* * * *

id1

sname

(g,h,i)
Course

(I, j)
Tutor

(i)
Student

(a)
Employee

hname

(j)
Lecturer

(j)
Professor

id2 id5

?

Head

?

+

id3

*

+

Idref
43

id4

idref
5 iname

Department

idref
2

(g)
Lab

(g)
Lecture

(i)
Artifact25

|

idref
8 (c, k, h)

Instructor

id8

lbname ltname

| *

Evaluation

fname (d)

Full Time

(d)
Part Time

(h)
Artifact2

pname

idref
2

Age

(e)
Retirement
Plan

(f)
Hourly
Rate

Fig. 9.19 A minimum fragmented XML schema with data redundancy

The XML document of Fig. 9.19 has six fragments (branches) under the root ele-
ment Teaching which is fewer than the ten fragments in the initial XML schema
design in case study.
Nevertheless, the element RetirementPlan contains repeating data of Age 65
which causes data redundancy in the element Retirement Plan with same age 65 in
two occurrence.
Step 5—Since more than one full-time instructor may have the same retirement
plan, the attribute values of a retirement plan may have to appear more than once.
Both cases may lead to data redundancy. We need to replace data redundant element
RetirementPlan by a nonreplicate element RetirementPlan such that it links with its
original parent element FullTime with id and idref.
Similarly, Part Time Instructors may have same Hourly Rate. As a result, we also
replace data redundant element PartTime by a nonreplicate fragment which links it
with its original parent element PartTime with id and idref to eliminate data redun-