Database Reference
In-Depth Information
3
the relational Model
and Normalization
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To understand basic relational terminology
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To understand the characteristics of relations
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To understand alternative terminology used in describing
the relational model
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To be able to identify functional dependencies,
determinants, and dependent attributes
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To identify primary, candidate, and composite keys
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To be able to identify possible insertion, deletion, and
update anomalies in a relation
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To be able to place a relation into BCNF normal form
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To understand the special importance of domain/key
normal form
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To be able to identify multivalued dependencies
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To be able to place a relation in fourth normal form
As we discussed
in Chapter 1, databases
arise from three sources: from existing data,
from the development of new information systems,
and from the redesign of existing databases. In this chapter
and the next, we consider the design of databases from existing data, such
as data from spreadsheets or extracts of existing databases.
The premise of Chapters 3 and 4 is that you have received one or more
tables of data from some source that are to be stored in a new database. The
question is: Should this data be stored as is, or should it be transformed in some
way before it is stored? For example, consider the two tables in the top part of
Figure 3-1. These are the SKU_DATA and ORDER_ITEM tables extracted from
the Cape Codd Outdoor Sports database as used in the database in Chapter 2.
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