Oracle中case when函數和decode函數

1、case when函數：

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;

以上兩種寫法均可。

2、decode函數：

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