Wiley Beginning MySQL 978-0-7645-7950-9 ユーザーズマニュアル
製品コード
978-0-7645-7950-9
4
Designing a Relational
Database
Chapter 1 introduced you to databases and databases management systems. As you’ll recall from
that discussion, a database is a collection of related data organized and classified in a structured for-
mat that is defined by metadata. Not all databases are structured the same, though, as can be attested
to by the different data models that have emerged over the years. Yet many of these models — and
subsequently the systems that were built on them — lacked the flexibility necessary to support
increasingly sophisticated software applications. One data model emerged that addressed the limita-
tions of its predecessors and provided the flexibility necessary to meet the demands of today’s appli-
cation technologies. This model — the relational model — has become the standard on which most
database management systems are now built.
that discussion, a database is a collection of related data organized and classified in a structured for-
mat that is defined by metadata. Not all databases are structured the same, though, as can be attested
to by the different data models that have emerged over the years. Yet many of these models — and
subsequently the systems that were built on them — lacked the flexibility necessary to support
increasingly sophisticated software applications. One data model emerged that addressed the limita-
tions of its predecessors and provided the flexibility necessary to meet the demands of today’s appli-
cation technologies. This model — the relational model — has become the standard on which most
database management systems are now built.
MySQL is one of the database management systems based on the relational model. As a result, to
design effective databases, you should have a good understanding of that model and how it applies
to database design. To that end, this chapter provides you with a conceptual overview of the rela-
tional model and explains the components that make up a relational database. The chapter also
discusses how data is organized in the relational model and how tables of data are related to one
another. Specifically, the chapter covers the following topics:
design effective databases, you should have a good understanding of that model and how it applies
to database design. To that end, this chapter provides you with a conceptual overview of the rela-
tional model and explains the components that make up a relational database. The chapter also
discusses how data is organized in the relational model and how tables of data are related to one
another. Specifically, the chapter covers the following topics:
❑
You are introduced to the relational model and the components that make up that model.
❑
You learn how data in a relational structure is organized according to normal forms,
which are prescriptive methods for organizing data in a relational database.
which are prescriptive methods for organizing data in a relational database.
❑
You are provided with the information necessary to identify the relationships between
tables in a relational database, including one-to-one, one-to-many, and many-to-many
relationships.
tables in a relational database, including one-to-one, one-to-many, and many-to-many
relationships.
❑
You learn how to create a data model. The process includes identifying entities, normaliz-
ing data, identifying relationships, and refining the data model.
ing data, identifying relationships, and refining the data model.
The Relational Model
The relational model first entered the database scene in 1970, when Dr. E. F. Codd published his sem-
inal work, “A Relational Model of Data for Large Shared Data Banks” in the journal Communication of
inal work, “A Relational Model of Data for Large Shared Data Banks” in the journal Communication of
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