Sql — Joins Notes Pdf

| student_id | course | |------------|-----------| | 1 | Math | | 2 | Science | | 4 | Art | Returns only rows with matching keys in BOTH tables.

📊 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. sql joins notes pdf

SELECT * FROM students LEFT JOIN courses ON students.id = courses.student_id; | id | name | student_id | course | |----|---------|------------|---------| | 1 | Alice | 1 | Math | | 2 | Bob | 2 | Science | | 3 | Charlie | NULL | NULL | Returns ALL rows from the right table, matched rows from the left table. NULL if no match. | student_id | course | |------------|-----------| | 1