其实这种用法在平常的操作中很常用

　　首先来展示下他的效果：

create table student(       sid int ,       sname varchar2(20),       sex varchar2(20)        ); create sequence seq_student_id increment by 1 start with 1 NOMAXVALUE;    insert into student values(seq_student_id.nextval,'yaobo','man');insert into student values(seq_student_id.nextval,'yaobo2','man'); insert into student values(seq_student_id.nextval,'yaobo3','woman'); insert into student values(seq_student_id.nextval,'yaobo4','man'); insert into student values(seq_student_id.nextval,'yaobo5','woman'); insert into student values(seq_student_id.nextval,'yaobo6','man33');

（1）第一种写法select case when sex = 'man' then '男' when sex = 'woman' then '女' else '人妖' end from student;　 这两种写法的所得的结果都是一样的	（2）第二种写法select case sex when 'man' then '男' when 'woman' then '女' else '人妖' end from student;

 

这个满足了when后面的第一个条件，后面的条件就会自动跳过