CROSS JOIN

CROSS JOIN returns every possible combination of rows from both tables without a join condition.

Source data — Pattern 6: Joins

All queries run against the shared employees and departments tables (see schema.sql). This pattern introduces the departments table. Topic 38 also needs a projects table, while topic 39 introduces a salary_grades table for non-equi joins.

CROSS JOIN — source table 1

CROSS JOIN — source table 2

CROSS JOIN — source table 3

CROSS JOIN — source table 4

What it does

CROSS JOIN returns every possible combination of rows from both tables without a join condition.

Problem

Generate all employee-department combinations.

SELECT e.first_name,
d.department_name
FROM employees e
CROSS JOIN departments d;

CROSS JOIN — result 1

Note

Only the first 12 rows are shown. The complete CROSS JOIN result contains 36 rows (6 employees × 6 departments).