ORACLE9I] DECODE, CASE WHEN THEN ELSE END

조건절 필요시 사용할수있는 함수들...

===================================================================================================================
DECODE(기준컬럼,조건값1,변경값1,조건값2,변경값2) AS 컬럼명

SELECT deptno,
                    DECODE(deptno, 10 , 'ACCOUNTING' ,
                                             20 , 'RESEARCH' ,
                                             30 , 'SALES' ,
                                             40 , 'OPERATIONS')
 FROM emp ;
===================================================================================================================


===================================================================================================================
CASE WHEN  조건절 THEN TRUE일경우값 ELSE FALSE 일경우값 END AS 컬럼명
CASE 기준컬럼 WHEN  조건값 THEN TRUE일경우값 ELSE FALSE 일경우값 END AS 컬럼명

EX>
SELECT DEPTNO, CASE WHEN DEPTNO='10' THEN '10번부서' ELSE (CASE WHEN DEPTNO='20' THEN '20번부서' ELSE '30번부서' END)  END AS DEPTRENAME
FROM EMP
===================================================================================================================