From 920facdffbb447a7ef777d4c5a936b96ec7fc259 Mon Sep 17 00:00:00 2001 From: syneffort Date: Mon, 26 Sep 2022 13:59:25 +0900 Subject: [PATCH] view --- view.sql | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/view.sql b/view.sql index e69de29..254dcfc 100644 --- a/view.sql +++ b/view.sql @@ -0,0 +1,42 @@ +USE Study +GO + +CREATE VIEW EMP30 +AS (SELECT * FROM EMPLOYEE WHERE DNO = 30) + +SELECT * FROM EMP30 WHERE SALARY >= 300 + +CREATE VIEW EMPAVGSAL +AS (SELECT AVG(SALARY) AS SALAVG FROM EMPLOYEE) + +SELECT * FROM EMPAVGSAL + +-- 인라인 뷰 +-- 조인 연산으로 조건에 맞는 모든 튜플쌍이 먼저 생성됨 +SELECT DNAME, AVG(SALARY) AS AVG_SAL +FROM EMPLOYEE AS E, DEPARTMENT AS D +WHERE E.DNO = D.DNO +GROUP BY DNAME +-- 원하는 튜플만 생성 후 조인하여 연상 효율성 증가 +SELECT DNAME, AVG_SAL +FROM ( + SELECT DNO, AVG(SALARY) AS AVG_SAL + FROM EMPLOYEE + GROUP BY DNO + ) AS S, DEPARTMENT D +WHERE S.DNO = D.DNO + +GO +-- WITH를 사용한 인라인뷰 +WITH S (DNO, AVG_SAL) +AS ( + SELECT DNO, AVG(SALARY) + FROM EMPLOYEE + GROUP BY DNO + ) +SELECT DNAME, AVG_SAL +FROM S, DEPARTMENT AS D +WHERE S.DNO = D.DNO + +-- 뷰 정의 보기 +SP_HELPTEXT EMP30 \ No newline at end of file