ER to Relational Mapping
Learn to translate a conceptual ER diagram into a physical relational schema.
We'll cover the following...
Imagine we’ve just finished designing a detailed blueprint for a new house.
This blueprint, our Entity-Relationship (ER) diagram, accurately depicts every room, door, and window. But a blueprint isn’t a house; we can’t live in it. We need to translate that design into actual bricks, wood, and mortar. In the world of databases, this is exactly what we do when we convert our ER diagram into a relational schema. This process, known as ER to relational mapping, is a crucial step that transforms our conceptual design into a physical database structure that we can actually build and utilize with SQL.
It’s the bridge from an idea to a working system.
By the end of this lesson, we will be able to:
Understand the importance of translating a conceptual ER diagram into a physical relational schema.
Apply a step-by-step process to map entities, attributes, and relationships.
Correctly convert one-to-one, one-to-many, and many-to-many relationships into tables and keys.
Handle more complex structures, such as weak entities, composite attributes, and multivalued attributes.
Let’s start building!
The goal of mapping
Before we dive into the specific rules, let’s clarify our goal.
The primary objective of ER to relational mapping is to convert the components of an ER diagram—entities, attributes, and relationships—into a set of relational tables with columns, primary keys, and foreign keys. This process ensures that all the information and constraints captured in our design are accurately represented in the final ...