Database Management Systems · Query languages

SQL joins

Combining rows from two or more tables based on a matching column.

Also known as: INNER JOIN, LEFT JOIN, join types.

Start a lesson on SQL joins

Learn first

• SQL filtering and projection: Picking which rows and columns you want back with SELECT and WHERE.

Leads to

• SQL subqueries: A query nested inside another query, used as a stand-in value or filter.
• Query processing and optimization: How the database decides which order to run joins and filters in, to answer a query as cheaply as possible.

Related topics

• SQL subqueries: A query nested inside another query, used as a stand-in value or filter.
• Query processing and optimization: How the database decides which order to run joins and filters in, to answer a query as cheaply as possible.