1.NVL
--找出不收取佣金或者是佣金低於100的僱員
解釋:SELECT * FROM emp WHERE nvl(comm,0)<100
comm IS NULL
SELECT * FROM emp WHERE comm is null and 0<100
comm IS NOT NULL
SELECT * FROM emp WHERE comm IS NOT NULL and comm<100
2.DECODE
SELECT
ename,
job,
sal,
DECODE(JOB, 'CLERK', '業務員','SALESMAN','銷售人員','MANAGER','經理','ANALYST','分析員','PRESIDENT','總裁') 職位 FROM emp;