#MYSQL查询将结果字段相乘

Question

    SELECT *,   
           CASE 
             WHEN(max(`priod_id`) > 4) THEN 
               "0.2" 
             ELSE 
               "0.25" 
           END AS PERCENTAGE,   
           COUNT(priod_id) as HOURS,
           COUNT(CASE 
                   WHEN nota_id = '1' THEN 
                     1 
                 END) AS PR
      FROM `attendance_tbl` A 
     WHERE DATE(attend_date) BETWEEN DATE('2018-08-01') AND DATE('2018-08-31') 
       AND sid = '60' 
  GROUP BY DATE(attend_date)

我们需要将PERCENTAGE和PR相乘 （PERCENTAGE * PR）总计
请告诉我们一种解决查询的技术。

Answer 1

一种方法是从现有scipy查询的结果集中获取Derived Table。之后，您可以在派生表的外部SELECT子句SELECT中执行各种操作（例如：此处的乘法）。请尝试以下操作：

FROM