2.2JOIN Types

JOIN Type	Returns	Use Case
INNER JOIN	Only matching rows from both tables	Orders with their items
LEFT JOIN	All rows from left, matching from right (NULL if none)	Users who may or may not have orders
RIGHT JOIN	All rows from right, matching from left (NULL if none)	Less common; same as LEFT JOIN with tables swapped
FULL OUTER JOIN	All rows from both tables	Orphaned records on both sides
CROSS JOIN	Every combination of rows	Generating test data combinations

Visual Understanding

INNER JOIN:     Only where both tables have matching data
LEFT JOIN:      Everything from left table + matching from right
RIGHT JOIN:     Everything from right table + matching from left
FULL OUTER:     Everything from both, NULLs where no match