Sql Joins Notes Pdf |link| Instant

SELECT * FROM students CROSS JOIN courses; Result: 3 × 3 = 9 rows. A table joined with itself. Useful for hierarchical data (e.g., employee-manager).

1. What is a JOIN? A JOIN clause is used to combine rows from two or more tables based on a related column between them. sql joins notes pdf

📊 Intersection of A and B. 3.2 LEFT JOIN (or LEFT OUTER JOIN) Returns ALL rows from the left table, matched rows from the right table. NULL if no match. SELECT * FROM students CROSS JOIN courses; Result: