Organizing data into tables

A database would have more than one table. One of the ways to plan out the separation of information into tables is to use the Entity Relationship Model (ERM).

ER diagrams is a visual tool created in 1971 to conceptualize modeling of DBMS. Understanding ERM goes hand in hand with working with multiple tables in a database. In terms of a DBMS, an entity is a table or attribute of a table in a database. By showing relationships among tables and their attributes, ER diagram shows the logical structure of a database.

Entity Relationship Diagram

An ER diagram has three main components: Entity, Attribute, and Relationship.

1. Entity is represented by a rectangle
2. Attribute is represented by an oval, could be a key attribute, composite attribute, multivalued attribute, or derived attribute.
3. Relationship is represented by a diamond shape. Could be one to one, one to many, many to one, or many to many.