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Designing databasesThe first step in creating a relational database is to construct a data model, which is a precise, complete definition of the data you want to store. After you prepare your data model, you must implement it as a database and tables. To implement your data model, you first select a data type for each column and then you create a database and tables and populate the tables with data. You can also implement fragmentation strategies and control access to your data.
Designing and Implementing a DatabaseThese topics provide information to help you design, implement, and manage your HCL® OneDB® databases. It includes data models that illustrate different approaches to database design and shows you how to use structured query language (SQL) to implement and manage your databases.The HCL OneDB™ Database Design and Implementation Guide provides information to help you design, implement, and manage your HCL® OneDB® databases. It includes data models that illustrate different approaches to database design and shows you how to use structured query language (SQL) to implement and manage your databases.
Basics of database design and implementation
Build a relational data model
Identify and define principal data objects
Discover entities
Telephone directory example
Unitary entities

Unitary entities

Names can be split into personal names and corporate names. You decide that all names should have the same features in this model; that is, you do not plan to record different information about a company than you would record about a person. Likewise, you decide that only one kind of address exists; you are not required to treat home addresses differently from business addresses.

However, you also realize that more than one kind of telephone number exists. Voice numbers are answered by a person, fax numbers connect to a fax machine, and modem numbers connect to a computer. You decide that you want to record different information about each kind of number, so these three types are different entities.

For the personal telephone directory example, you decide that you want to keep track of the following entities:

Name
Address (mailing)
Telephone number (voice)
Telephone number (fax)
Telephone number (modem)