简单问题,case语句?在线等!

Question

select b.province_name,        
       (case  
       when  c.type_id=101 then set c.type_name="钻石卡"
       when  c.type_id=102 then set c.type_name="金卡"
       when  c.type_id=103 then set c.type_name= "银卡"
      else set type_name= "普通卡" 
       end case)  type_name
       sum(a.points_earned) history_earned,sum(a.points_balance) points_balance
from ecc_bj.ecc_points a,ecc_bj.ecc_sv_province b,ecc_bj.ecc_account_grade c
where a.account_grade=c.type_id and substr(a.customer_id,1,2)=b.province_id
group by c.type_name,b.province_name错误缺少表达式。
请问我该怎么改啊，case语句该怎么改昵

Answer 1

select b.province_name,
       case
         when c.type_id = 101 then
          '钻石卡'
         when c.type_id = 102 then
          '金卡'
         when c.type_id = 103 then
          '银卡'
         else
          '普通卡'
       end type_name,
       sum(a.points_earned) history_earned,
       sum(a.points_balance) points_balance
  from ecc_bj.ecc_points        a,
       ecc_bj.ecc_sv_province   b,
       ecc_bj.ecc_account_grade c
 where a.account_grade = c.type_id
   and substr(a.customer_id, 1, 2) = b.province_id
 group by c.type_name, b.province_name

Answer 2

select b.province_name,
       (case
         when c.type_id = 101 then
          '钻石卡'
         when c.type_id = 102 then
          '金卡'
         when c.type_id = 103 then
          '银卡'
         else
          '普通卡'
       end )type_name,
       sum(a.points_earned) history_earned,
       sum(a.points_balance) points_balance
  from ecc_bj.ecc_points        a,
       ecc_bj.ecc_sv_province   b,
       ecc_bj.ecc_account_grade c
 where a.account_grade = c.type_id
   and substr(a.customer_id, 1, 2) = b.province_id
 group by c.type_name, b.province_name