CROSS JOIN
JoinReturns the Cartesian product of two tables — every combination of rows.
Syntax
SELECT cols FROM t1 CROSS JOIN t2
Example
SELECT colors.name, sizes.label FROM colors CROSS JOIN sizes;
About SQL CROSS JOIN
The CROSS JOIN keyword belongs to the Join category of SQL statements. Returns the Cartesian product of two tables — every combination of rows. Understanding this command is essential for any developer working with relational databases like PostgreSQL, MySQL, SQLite, or SQL Server.
SQL (Structured Query Language) is the standard language for managing and querying relational databases. The CROSS JOIN statement is supported across all major database systems, though specific syntax may vary slightly between PostgreSQL, MySQL, MariaDB, Oracle, SQL Server, and SQLite. Always consult your database's documentation for vendor-specific features and limitations.
Best practices for using CROSS JOIN: always test queries on a development database before running them in production, use parameterized queries to prevent SQL injection, and leverage EXPLAIN to understand query performance. For complex queries, consider using CTEs (Common Table Expressions) to improve readability and maintainability.