두 개 이상의 테이블들을 연결 또는 결합하여 데이터를 출력하는 것
SELECT *
FROM employee INNER JOIN department
ON employee.DepartmentID = department.DepartmentID;
SELECT * FROM employee CROSS JOIN department;
SELECT *
FROM employee FULL OUTER JOIN department
ON employee.DepartmentID = department.DepartmentID;
SELECT *
FROM employee LEFT OUTER JOIN department
ON employee.DepartmentID = department.DepartmentID;