Database Reference
In-Depth Information
Figure 7.20. Resolving the multivalued field in the INSTRUCTORS table
Note that the new INSTRUCTOR CATEGORIES table is free from the problems typically
associated with multivalued fields because C
ATEGORY
T
AUGHT
is a
single-value
field. You
can easily retrieve information for a particular instructor or category, and you can sort the
records in a meaningful manner. Also note that the I
NST
F
IRST
N
AME
and I
NST
L
AST
N
AME
fields retain their names in the new table, making them compliant with the fifth element of
an ideal field.
Although the new table contains redundant data, the redundancy is acceptable because it
is
minimal.
It's a fact of life that a relational database will always contain some amount of
redundant data. Your goal as the database architect is to make certain that it has only an
absolute minimum
amount of redundant data.
