Databases Beginner

What is Primary Key?

A column or set of columns that uniquely identifies each row in a database table.

A primary key ensures every row in a table is unique and identifiable. It cannot contain NULL values and must be unique across all rows. Common choices include auto-incrementing integers (SERIAL) or UUIDs.

Primary keys are automatically indexed for fast lookups. Composite primary keys use multiple columns together. Primary keys are referenced by foreign keys in other tables to create relationships.

Learn More About This Topic

Database Design & Modeling Fundamentals

Related reading

SQL for Absolute Beginners

Related reading

Redis Fundamentals

Related reading

Related Terms

EXPLAIN ANALYZE

A PostgreSQL command that shows the execution plan of a query along with actual runtime statistics for performance tuning.

A set of four properties (Atomicity, Consistency, Isolation, Durability) that guarantee reliable database transactions.

Write-Ahead Log (WAL)

A technique where changes are first written to a log before being applied to the database, ensuring crash recovery and data integrity.

A version-controlled change to a database schema that can be applied and reversed systematically.

A technique of dividing large database tables into smaller, more manageable segments while maintaining a single logical table.

An SQL operation that combines rows from two or more tables based on a related column between them.

View All Databases Terms →