SELECT CASE RegType WHEN 1 THEN '月卡' 
                    WHEN 0 THEN '周卡' 
                    WHEN 2 THEN '季度卡' 
                    WHEN 3 THEN '年卡'    
       ELSE '未知卡类型'                       
       END AS '卡类型'       
FROM SL_Register_Info