Primary Key

A primary key is a database concept that uniquely identifies each record in a table, ensuring no duplicate or null values exist for that column or set of columns. It enforces entity integrity and serves as the main reference point for relationships between tables in relational databases.

Also known as: PK, Primary Key Constraint, Unique Identifier, Primary Index, Key Field

Why learn Primary Key?

Developers should use primary keys when designing relational database schemas to guarantee data uniqueness and enable efficient data retrieval through indexing. They are essential for establishing foreign key relationships, which maintain referential integrity and support complex queries in applications like e-commerce systems or user management platforms.

Learning Resources

• tutorial: W3Schools SQL Primary Key
• docs: PostgreSQL Documentation on Primary Keys
• course: Khan Academy Intro to SQL: Querying and Managing Data
• video: YouTube: Database Design - Primary Keys Explained