Designing Tables

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In a relational database, the database object that represents a single entity is a table, which is a two-dimensional matrix of rows and columns. Each column in a table represents an attribute. Each row in the table represents a specific instance of the entity. After you identify the entities and attributes, create the data model, which serves as a logical design framework for creating your InterBase database. The data model maps entities and attributes to InterBase tables and columns, and is a detailed description of the database–the tables, the columns, the properties of the columns, and the relationships between tables and columns.

The example below shows how the EMPLOYEE entity from the entities/attributes list has been converted to a table.

EMPLOYEE table

EMP_NO	LAST_NAME	FIRST_NAME	DEPT_NO	JOB_CODE	PHONE_EXT	SALARY
24	Smith	John	100	Eng	4968	64000
48	Carter	Catherine	900	Sales	4967	72500
36	Smith	Jane	600	Admin	4800	37500

Each row in the EMPLOYEE table represents a single employee. EMP_NO, LAST_NAME, FIRST_NAME, DEPT_NO, JOB_CODE, PHONE_EXT, and SALARY are the columns that represent employee attributes. When the table is populated with data, rows are added to the table, and a value is stored at the intersection of each row and column, called a field. In the EMPLOYEE table, “Smith” is a data value that resides in a single field of an employee record.

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• Determining Unique Attributes (Designing Databases)