SQL 셀프 조인

1 개요

SQL self-join

SQL 셀프 조인

CREATE TABLE newEmployees (EmployeeID int(11), LastName varchar(32), Country varchar(32), DepartmentID int(11));
INSERT INTO newEmployees (EmployeeID, LastName, Country, DepartmentID) VALUES
	(123, 'Rafferty',   'Australia',     31  ),
	(124, 'Jones',      'Australia',     33  ),
	(145, 'Heisenberg', 'Australia',     33  ),
	(201, 'Robinson',   'United States', 34  ),
	(305, 'Smith',      'Germany',       34  ),
	(306, 'Williams',   'Germany',       NULL);

SELECT A.EmployeeID, A.LastName, B.EmployeeID, B.LastName, A.Country
FROM newEmployees A JOIN newEmployees B ON A.Country = B.Country
WHERE A.EmployeeID < B.EmployeeID
ORDER BY A.EmployeeID, B.EmployeeID

2 같이 보기

• 셀프
• SQL 조인
• R 셀프 조인
• Pandas 셀프 조인

3 참고

• 영어 위키백과 "Join (SQL)#Self-join"