09.별칭

as 별칭(alias)

값에 별칭을 주어 별칭의 형태로 할 수있는 역할

 select empno as"사번",ename as "사원명",sal as "월급" from emp where sal >=3000;

  사번	사원명	월급
7788	SCOTT	3000
7839	KING	5000
7902	FORD	3000 

아래와 같다

 select empno "사번", ename "사원명", sal "월급" from emp where sal >=3000; 

 

• distinct (중복제거)

select job from emp;

JOB
CLERK
SALESMAN
SALESMAN
MANAGER
SALESMAN
MANAGER
MANAGER
ANALYST
PRESIDENT
SALESMAN
CLERK
CLERK
ANALYST
CLERK

 

select distinct job from emp;

 JOB
CLERK
SALESMAN
PRESIDENT
MANAGER
ANALYST