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What is a Relational Database

A relational database is a type of database that organizes data into tables with rows and columns where the relationships between these tables are established through shared data points.

Tables

The fundamental building blocks of a relational database are tables.

Each table represents an entity which is a real world object or concept like a customer, product or order.

Rows: Represents individual entries or records within a table for example a single customer.

Columns: Represents the attributes or properties of the entity for example customer name, address, phone number.

Relationships

The heart of a relational database. These connections define how data relate to one another.

Primary Key: A unique identifier for each record/row within a table (Customer ID, Product ID).

Foreign Key: A column in one table that references the primary key of another table, creating a link between them (for example an Order table might have a Customer ID column as a foreign key to link each order to a customer).

Example

Imagine these simple tables:

Customers:

  • CustomerID (Primary Key)
  • Name
  • Address

Orders:

  • OrderID (Primary Key)
  • CustomerID (Foreign Key)
  • OrderDate
  • ProductID (Foreign Key)

Advantages of Relational Databases

Data Integrity: The structure enforces consistency and prevents data duplication.

Flexibility: You can query and manipulate data in sophisticated ways, joining tables to create complex reports.

Scalability: Handles large amounts of data efficiently.

Widely used: Supported by a vast ecosystem of tools and technologies.

SQL

Structured Query Language (SQL) is the standard language for interacting with relational databases, creating tables, inserting data, running queries.

Real World Examples

Relational databases power a bunch of different systems:

  • Customer relationship management (CRM) systems
  • E-commerce platforms
  • Inventory management systems
  • Financial systems

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