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Chapter 3
The Relational Database Model
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Structure and Organize Data
The Relational Database Model
The relational database model
Let us take a look at some important terminology:
Database
A collection of information that you organize and access
according to the logical structure of that information.
You can think of a database as a group of data that is
organized into the logical structure of the business
information.
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Structure and Organize Data
The Relational Database Model
The relational database model
Continue with terminology:
Relational database model
uses a series of logically related two-dimensional tables
(called relations) or files to store information in the form
of a database.
Note that a relational table contains a group of related data.
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Structure and Organize Data
The Relational Database Model
The relational database model
Continue with terminology:
Relation
describes each two-dimensional table or file in the
relational model.
The word relation here is in reference to the collection of
the data within one specific table.
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Structure and Organize Data
The Relational Database Model
The relational database model
By carefully examining the definition given to
“relational databases” we can clearly identify
two parts to it:
1.
2.
Information – stored in a series of two
dimensional tables, files, or relations.
Logical structure of the information.
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Structure and Organize Data
The Relational Database Model
The relational database model
Figure 3.2
A Portion of an
Inventory
Database and Data
Dictionary
page 81
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Structure and Organize Data
The Relational Database Model
The relational database model
In using the relational database model three
distinct characteristics are important to
understand:
1.
2.
3.
Collection of data = Information, hence
logical structure
Logical ties
Integrity constraints
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Structure and Organize Data
The Relational Database Model
The relational database model
Collection of data = Information,
hence logical structure
1.
2.
Information important to the business is identified
(ex. Orders, facility, suppliers, parts…).
Data that is related to each other and
contained/constitutes the information needs to be
identified.
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Structure and Organize Data
The Relational Database Model
The relational database model

To identify the and information into its
logical structures you need to create a
data dictionary.

Data dictionary - contains the logical
structure for the information.
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Structure and Organize Data
The Relational Database Model
The relational database model
Figure 3.2
A Portion of an
Inventory Database
and Data Dictionary
page 81
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Structure and Organize Data
The Relational Database Model
The relational database model



Once data and information has been put in a
logical structure, the information contained in
the database requires to be related to each
other.
An example would be relating the customer
information to the order information.
This is done using primary and foreign keys.
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Structure and Organize Data
The Relational Database Model
The relational database model

Primary key - a field/data (or group of
fields in some cases) that uniquely
describes each record.

Foreign key - a field/data that is a primary
key in another file.
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Structure and Organize Data
The Relational Database Model
The relational database model
Figure 3.2
A Portion of an Inventory
Database and Data
Dictionary
page 81
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Structure and Organize Data
The Relational Database Model
The relational database model
Team Work

Integrity
constraints – rules
that help ensure the
quality of the
information.
Primary Keys,
Foreign Keys, and
Integrity Constraints
(p. 84)
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