mssql_Study/join (cartesian).sql

USE Study
GO

SELECT * FROM EMPLOYEE
SELECT * FROM DEPARTMENT

-- Cartesian product: <EFBFBD><EFBFBD><EFBFBD><EFBFBD> Ʃ<EFBFBD>ý<EFBFBD> <EFBFBD><EFBFBD><EFBFBD><EFBFBD> (same as Cross join)
SELECT * FROM EMPLOYEE, DEPARTMENT

select * from EMPLOYEE
select * from SALGRADE

-- Theta join
SELECT ENAME, GRADE
FROM EMPLOYEE, SALGRADE
WHERE LOWSAL <= SALARY AND SALARY <= HIGHSAL

SELECT ENAME, GRADE
FROM EMPLOYEE, SALGRADE
WHERE SALARY BETWEEN LOWSAL AND HIGHSAL

-- Self join
SELECT E.ENAME AS ENAME, M.ENAME AS MANAGER
FROM EMPLOYEE AS E, EMPLOYEE AS M
WHERE E.MANAGER = M.ENO

-- Mulitple join
SELECT ENAME, GRADE, DNAME
FROM EMPLOYEE, SALGRADE, DEPARTMENT
WHERE SALARY BETWEEN LOWSAL AND HIGHSAL
	AND EMPLOYEE.DNO = DEPARTMENT.DNO