Oracle中case when函数和decode函数

1、case when函数：

select ename,case deptno 
  when 10 then 'ACCOUNTING' 
  when 20 then 'RESEARCH' 
  else 'SALES' end from emp;
    
select ename,case  
when deptno=10 then 'ACCOUNTING' 
  when deptno=20 then 'RESEARCH' 
    else 'SALES' end from emp;

以上两种写法均可。

2、decode函数：

select ename,decode(deptno,10,'ACCOUNTING',20,'RESEARCH',30,'SALES','OTHERS') from emp;