~2023.02/DB(SQL)

가상 테이블인 뷰

-- 가상 테이블인 '뷰' -- 기본 테이블 생성하기 DROP TABLE DEPT_COPY; CREATE TABLE DEPT_COPY AS SELECT * FROM DEPT; DROP TABLE EMP_COPY; CREATE TABLE EMP_COPY AS SELECT * FROM EMP; SELECT * FROM DEPT_COPY; SELECT * FROM EMP_COPY; -- 뷰 정의하기 CREATE OR REPLACE VIEW EMP_VIEW30 AS SELECT EMPNO, ENAME, SAL, DEPTNO FROM EMP_COPY WHERE DEPTNO=30; -- "insufficient privileges" SELECT * FROM EMP_VIEW30; -- 단순 뷰의 컬럼에 별칭 부여하기..

데이터 무결성을 위한 제약 조건

-- 1. CREATE TABLE ORDERS( ORDER_ID NUMBER(12, 0), ORDER_DATE DATE, ORDER_MODE VARCHAR2(8), CUSTOMER_ID NUMBER(6, 0), ORDER_STATUS NUMBER(2, 0), ORDER_TOTAL NUMBER(8, 2) DEFAULT 0, SALES_REP_ID NUMBER(6, 0), PROMOTION_ID NUMBER(6, 0) --CONSTRAINT ORDERS_ORDER_ID_PK PRIMARY KEY(ORDER_ID), --CONSTRAINT ORDERS_ORDER_MODE_CK CHECK(ORDER_MODE IN ('direct', 'online')) ); ALTER TABLE ORDERS ADD CONSTRA..