mysql - 重叠预订的最小和最大计数

Question

我有一个预订系统，其中有多个同时预订，每个预订都有一个计数。我需要获取指定日期范围(在本例中为一天)的最小值和最大值。我发现了一些很好的代码 here ，在测试中效果很好。但在我的实现中，它在这个特定的实例中失败了:

• 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。

如何解决这个问题？

这是一个例子:

此预订具有以下属性: 列表(多个预订可以拥有的 ID，但在本例中只有一个):2f23f23f

开始日期:2016-01-15 08:00:00

结束日期:2016-01-17 08:00:00

状态:事件

数量:1

结果:

最小计数:0

最大计数:0

它应该返回:

最小计数:0

最大计数:1

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

最小计数:1

最大计数: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

哇，好吧，这就是答案。原著显然并不完整。它需要包括所请求的时间范围的开始/结束日期。

  UNION
    SELECT :date_start
  UNION
    SELECT :date_end

完整代码:

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