SQL> select ename,sal from emp; ENAME SAL ---------- ---------- SMITH 800 ALLEN 1600 WARD 1250 JONES 2975 MARTIN 1250 BLAKE 2850 CLARK 2450 SCOTT 3000 KING 5000 TURNER 1500 ADAMS 1100 ENAME SAL ---------- ---------- JAMES 950 FORD 3000 MILLER 1300 14 rows selected. SQL> select ename,sal, 2 case when sal<2000 then 'low' 3 when sal>=2000 and sal<4000 then 'mid' 4 when sal>=4000 then 'high' end as status 5 from emp; ENAME SAL STAT ---------- ---------- ---- SMITH 800 low ALLEN 1600 low WARD 1250 low JONES 2975 mid MARTIN 1250 low BLAKE 2850 mid CLARK 2450 mid SCOTT 3000 mid KING 5000 high TURNER 1500 low ADAMS 1100 low ENAME SAL STAT ---------- ---------- ---- JAMES 950 low FORD 3000 mid MILLER 1300 low 14 rows selected. 关于CASE更详细的用法可以参考下面的文章 http://blog.youkuaiyun.com/wh62592855/archive/2009/11/01/4753853.aspx