Database.What is a “relational data model”?

The relational data model is a way to organize data in a database using tables (also called relations). It was introduced by E. F. Codd in 1970 and is the foundation of relational databases like MySQL, PostgreSQL, and Oracle.

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🧱 Key Concepts:

1. Relation (Table)
   • A set of rows and columns.
   • Each table represents a type of entity (e.g., Users, Orders).
2. Tuple (Row)
   • A single record in a table.
   • Represents one instance of the entity.
3. Attribute (Column)
   • A field or property of the entity (e.g., Name, Email).
   • Each column has a data type (e.g., INTEGER, VARCHAR).
4. Primary Key
   • A column (or group of columns) that uniquely identifies each row in a table.
5. Foreign Key
   • A column that links to the primary key of another table, establishing a relationship.

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📊 Example: Two Related Tables

Customers

CustomerID (PK)	Name	Email
1	Alice	alice@mail.com
2	Bob	bob@mail.com

Orders

OrderID (PK)	CustomerID (FK)	Product
101	1	Laptop
102	2	Smartphone

In this example:

• CustomerID in Customers is the primary key.
• CustomerID in Orders is a foreign key linking to Customers.

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✅ Benefits of the Relational Model:

• Data integrity via keys and constraints
• Easier querying using SQL
• Normalization helps reduce data redundancy
• Strong theoretical foundation