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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.

Related Terms

EXPLAIN Plan
A database command that shows how the query planner will execute a SQL query, revealing join methods, scan types, and estimated costs.
Deadlock
A situation where two or more transactions permanently block each other by each holding locks that the other needs.
Database Constraint
Rules enforced by the database to maintain data integrity, including NOT NULL, UNIQUE, CHECK, PRIMARY KEY, and FOREIGN KEY.
Trigger
A database object that automatically executes a specified function when certain events (INSERT, UPDATE, DELETE) occur on a table.
PostgreSQL
An advanced open-source relational database known for its reliability, feature richness, and standards compliance.
Window Function
An SQL function that performs calculations across a set of rows related to the current row without collapsing the result set.
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