计算多个日期范围内给定日期之间的价格 [英] calculate price between given dates in multiple ranges

问题描述

您好，以下代码在两个或多个范围内使用时效果很好，但在开始日期和结束日期在相同范围内时效果不佳.当开始日期和结束日期在相同范围内时，totalprice将返回额外的一天.因此，一晚的总价增加了一倍.

Hi the following code works well when used over two or more ranges but not when the start date and end date are in the same range. When the start date and end date are in the same range the totalprice returns an extra day. Hence the totalprice for one night is doubled.

这是mysql表；

CREATE TABLE rooms (
 Hotel_id INT,
 Room_id INT,
 Room_type VARCHAR(20),
 Start_date DATE,
 End_date DATE,
 Price INT
);

INSERT INTO rooms VALUES
(   13   ,     2     ,   'standard' ,  '2012-08-01' ,  '2012-08-15'  , 7000),
(   13   ,     2     ,   'standard' ,  '2012-08-16' ,  '2012-08-31'  , 7500),
(   13   ,     2     ,   'standard' ,  '2012-09-01' ,  '2012-09-30'  , 6000),
(   13   ,     3     ,    'luxury'  ,  '2012-08-01' ,  '2012-08-15'  , 9000),
(   13   ,     3     ,    'luxury'  ,  '2012-08-16' ,  '2012-08-31'  , 10000),
(   13   ,     3     ,    'luxury'  ,  '2012-09-01' ,  '2012-09-30'  , 9500),
(   13   ,     3     ,    'luxury'  ,  '2012-10-01' ,  '2012-10-15'  , 15000);

这是代码；

SELECT     SUM(
           CASE WHEN a.Start_date = b.min_sd AND a.Start_date <> b.max_sd THEN
                    (DATEDIFF(a.End_date, '2012-09-03')+1) * a.Price
                WHEN a.Start_date = b.max_sd AND a.Start_date <> b.min_sd THEN
                    DATEDIFF('2012-09-04', a.Start_date) * a.Price
                WHEN (a.Start_date,a.Start_date) IN ((b.min_sd,b.max_sd)) THEN
                    (DATEDIFF('2012-09-04', '2012-09-03')+1) * a.Price
                WHEN a.Start_date NOT IN (b.min_sd, b.max_sd)             THEN
                    (DATEDIFF(a.End_date, a.Start_date)+1) * a.Price
           END 
       ) AS totalprice
FROM       rooms a
CROSS JOIN (
       SELECT MIN(Start_date) AS min_sd,
              MAX(Start_date) AS max_sd
       FROM   rooms
       WHERE  Room_type   = 'luxury'     AND
              End_date   >= '2012-09-03' AND
              Start_date <= '2012-09-04'
       ) b
WHERE      a.Room_type   = 'luxury'     AND
       a.End_date   >= '2012-09-03' AND
       a.Start_date <= '2012-09-04';

推荐答案

您可以使用如下查询:

SELECT
  SUM(
    DateDiff(
      Least(End_Date + INTERVAL 1 DAY, '2012-09-04'),
      Greatest(Start_Date, '2012-08-31')
    ) * Price
  )
FROM
  rooms a
WHERE
  a.Room_type   = 'luxury'     AND
  a.End_date   >= '2012-08-31' AND
  a.Start_date <  '2012-09-04';

请在此处看到小提琴.

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