A well-designed database is like a well-planned city—it saves time, avoids confusion, and scales easily as things grow.

In Episode 7 of the Database Series, we’ll walk you through the basics of designing a database from scratch, including how to:

• Define tables and relationships
• Identify entities and attributes
• Use ER diagrams to map everything visually

Let’s get started!

 What Is Database Design?

Database design is the process of structuring how data is stored and connected within a system.

Why it matters:

• Ensures data is organized and easy to access
• Reduces duplication and errors
• Makes querying and reporting faster and cleaner

 Step 1: Identify Entities and Attributes

 What’s an Entity?

An entity is any object, person, place, or concept you want to store data about.

Examples:

• Student
• Course
• Product
• Customer

 What’s an Attribute?

Attributes are the details or characteristics of an entity.

Example:
For a Student entity, attributes might be:

• student_id
• name
• email
• date_of_birth

 Step 2: Map Out Relationships Between Entities

After listing entities and attributes, the next step is to define how entities are related.

 Common Relationship Types:

Relationship Type	Example	Description
One-to-One	One user → one profile	Rare but used for tightly linked data
One-to-Many	One teacher → many students	Most common
Many-to-Many	Students ↔ Courses	Requires a bridge table

Related: Primary Key vs Foreign Key in SQL

 Step 3: Create an ER Diagram

An ER (Entity-Relationship) diagram visually shows:

• Entities (tables)
• Attributes (columns)
• Relationships (lines/arrows between tables)

 ER Diagram Symbols:

•  Entity → represented as a rectangle
•  Attribute → oval shape
•  Relationship → line connecting entities

 Sample Mini ER Diagram

+————-+         +————–+

|  Students   |         |  Enrollments |

+————-+         +————–+

| student_id  |    ◄────────|                           student_id   |

| name        |         | course_id    |────────►+———–+

| email       |         | date_enrolled|                       | Courses   |

+————-+         +————–+                     +———–+

| course_id |

| name      |

+———–+

 Step 4: Normalize Your Data

Normalization is the process of organizing data to:

• Avoid redundancy (repeating info)
• Improve efficiency
• Ensure each table handles one type of data

You break large, complex tables into smaller ones and link them using keys.

 Best Practices for Database Design

1. Use meaningful table and column names
   → e.g., student_id not just id
2. Define primary keys for all tables
3. Use foreign keys to maintain relationships
4. Avoid storing repeated data (normalize!)
5. Use the right data types (INT, VARCHAR, DATE, etc.)
6. Plan with diagrams before writing code
7. Think ahead for scalability (future-proofing)

 Summary: Database Design in 4 Steps

Step	Action
1. Define Entities	What are you storing?
2. List Attributes	What details do you need about each entity?
3. Map Relationships	How are entities connected?
4. Create ER Diagram	Visualize the full structure

A good design now prevents a messy database later.