ER Diagrams are high-level conceptual models used in the design of database applications.

The model shown above is navigatable and identifies the different notations used in ERD's to describe a problem database.

An example of a COMPANY database is illustrated in the world shown. It allows user-defined requirements that are normally specified at the beginning of a database definition to be met without any conflicting factors.

The Company data is as follows:
Company is organized into departments,Each department has a unique number,and a particular employee who manages the department.A department may have several locations.
A department controls a number of projects, each has a unique name, unique number and single location.
Each employee's name social sec. num, Bdate & sex are stored.An employee is assigned to one dept. but may work on several projects not necessarily controlled by the same dept.Each employee has a dependent we keep track of.