Database Reference
In-Depth Information
3.7 MAPPING THE ENTITY DIAGRAM TO A RELATIONAL DATABASE
Converting an ER diagram into a database is called mapping. A relational database is also
represented by two-dimensional tables called "relations." The tables are composed of rows
and columns. The rows are called tuples and the columns, attributes. All attributes of a re-
lation must be atomic and keys must not be null. Mapping rules are required to convert ER
diagram into a relational database.
3.7.1 Rule 1: Mapping of strong entities
For strong entities, create a new table/relation for each strong entity. The indicated key of
the strong entity is made the primary key of the table. If there is more than one candidate
key in ER diagram, choose one as a primary key.
