重叠预订的最小和最大数量

Question

我有一个预订系统，可以同时进行多个预订，每个预订都有一个计数。 我需要获取指定日期范围内的最小值和最大值（在这种情况下为一天）。 我在这里找到了一些不错的代码，在测试中效果很好。 但是在我的实现中，它在此特定实例中失败：

• 它不计算在查询范围之前开始并在查询范围内结束的预订。

我该如何解决？

这是一个例子：

该预订具有以下属性：列表（多个预订可以具有的ID，在这种情况下只有一个）：2f23f23f

date_start：2016-01-15 08:00:00

date_end：2016-01-17 08:00:00

状态：有效

数：1

结果：

最小计数：0

max_count：0

它应该返回：

最小计数：0

max_count：1

如果我们查询的内容完全相同，但日期范围为2016-01-16 00:00:00-2016-01-16 23:59:59，则会返回正确的答案：

最小计数：1

max_count：1

这是MYSQL：

SELECT
    MAX(simultaneous) AS max_count,
    MIN(simultaneous) AS min_count
FROM (
  SELECT IFNULL(SUM(
      (
          CASE WHEN (
                listings = '2f23f23f'
                AND 
                    (state = 'active')
          )
          THEN count
          ELSE 0
          END
      )
    ),0) AS simultaneous
  FROM   bookings RIGHT JOIN (
    SELECT date_start AS boundary
    FROM   bookings
    WHERE date_start BETWEEN '2016-01-17 00:00:00' AND '2016-01-17 23:59:59'

  UNION
    SELECT date_end
    FROM   bookings
    WHERE  date_end BETWEEN '2016-01-17 00:00:00' AND '2016-01-17 23:59:59'

  UNION
    SELECT MAX(boundary)
    FROM (
      SELECT MAX(date_start) AS boundary
      FROM   bookings
      WHERE date_start <= '2016-01-17 00:00:00'

    UNION ALL
      SELECT MAX(date_end)
      FROM   bookings
      WHERE date_end <= '2016-01-17 23:59:59'

    ) t
  ) t ON date_start <= boundary AND boundary < date_end
  LEFT OUTER JOIN cart ON cart_bookings = id
  GROUP BY boundary
) t

Answer 1

哦，好的，这就是答案。 原始文件显然不完整。 它需要包括所请求时间范围的开始/结束日期。

  UNION
    SELECT :date_start
  UNION
    SELECT :date_end

完整的代码：

SELECT
    MAX(simultaneous) AS max_count,
    MIN(simultaneous) AS min_count
FROM (
  SELECT IFNULL(SUM(
      (
          CASE WHEN (
                listings = '2f23f23f'
                AND 
                    (state = 'active')
          )
          THEN count
          ELSE 0
          END
      )
    ),0) AS simultaneous
  FROM   bookings RIGHT JOIN (
    SELECT date_start AS boundary
    FROM   bookings
    WHERE date_start BETWEEN '2016-01-17 00:00:00' AND '2016-01-17 23:59:59'

  UNION
    SELECT date_end
    FROM   bookings
    WHERE  date_end BETWEEN '2016-01-17 00:00:00' AND '2016-01-17 23:59:59'

  UNION
    SELECT MAX(boundary)
    FROM (
      SELECT MAX(date_start) AS boundary
      FROM   bookings
      WHERE date_start <= '2016-01-17 00:00:00'

    UNION ALL
      SELECT MAX(date_end)
      FROM   bookings
      WHERE date_end <= '2016-01-17 23:59:59'

    ) t
  UNION
    SELECT :date_start
  UNION
    SELECT :date_end
  ) t ON date_start <= boundary AND boundary < date_end
  LEFT OUTER JOIN cart ON cart_bookings = id
  GROUP BY boundary
) t