Mysql 常用函数（4）- case 函数

CASE  <表达式>
   WHEN <值1> THEN <操作>
   WHEN <值2> THEN <操作>
   ...
   ELSE <操作>
END;

SELECT name,dept_id,
CASE
        dept_id 
        WHEN 0 THEN
        "实习生" 
        WHEN 1 THEN
        "销售部" 
        WHEN 2 THEN
        "信息部" 
        WHEN 2 THEN
        "财务部" ELSE "没有部门" 
    END AS "部门" 
FROM
    emp;

CASE
    WHEN <条件1> THEN <操作>
    WHEN <条件2> THEN <操作>
    ...
    ELSE <操作>
END;

select name,dept_id,
case 
when dept_id=1 and leader != 0 and is_enable !=0 then "销售部在职员工"
when dept_id =2 and leader = 0 then "信息部大佬"
when leader = 8 then "任我行大佬"
else "啥都不是"
end
from emp;