选择特定时间段内的所有可用项目

Question

所以我有2张桌子照顾和客户,就像这样

client {
  id,
  name
}

caring {
  id,
  startDate,
  endDate,
  clientId
}

我需要让所有在两个提供的日期之间至少有一天可用的客户,您可以看到我的屏幕截图作为参考.

截图我有两个客户端,我需要返回它们.如您所见,第一个客户在提供期间(16.5.-29.5.)之间有三个免费日(21.5.-23.5.),而第二个客户没有任何关怀期.

到目前为止,我尝试过这样的事情

SELECT * FROM client cl
WHERE cl.id NOT IN (SELECT clientId FROM caring 
WHERE endDate >= CURDATE() AND endDate <= DATE_ADD(CURDATE(), INTERVAL 14 DAY))

这个只返回没有照顾的客户.这部分是我需要的,因为此查询不包括我的屏幕截图中的第一个客户端.然后我尝试了下面的查询.

SELECT ca.startDate, ca.endDate, cl.firstName, cl.lastName
FROM caring ca
LEFT JOIN client cl on cl.id = ca.clientId
WHERE ca.startDate NOT IN (
    SELECT endDate
    FROM caring 
) AND ca.startDate <= '2017-05-29' AND ca.endDate >= '2017-05-16'

但我没有得到理想的结果.

任何想法我怎么能实现这一点,提前thx!

Answer 1

选择感兴趣的时间段内的护理，并将开始/结束日期分别限制在该时间段内。此限制将允许更轻松地计算“已预订”（即以后的非空闲天数）。

SELECT ca.id,
       -- Limit start/end dates to period of interest, respectively
       GREATEST (ca.startDate, '2017-05-16') AS `effectiveStartDate`,
       LEAST (ca.endDate, '2017-05-29') AS `effectiveEndDate`,
       ca.clientId
  FROM carings ca
 WHERE ca.startDate <= '2017-05-29' AND ca.endDate >= '2017-05-16';

接下来，计算预订天数：

DATEDIFF (DATE_ADD (LEAST (ca.endDate, '2017-05-29'), INTERVAL 1 DAY),
          GREATEST (ca.startDate, '2017-05-16'))
   AS `effectiveDays`

最后，过滤掉整个期间预订的客户。这是通过比较来完成的

• 每个客户的预订天数总和 ( GROUP BY) 至
• 整个期间的天数 ( HAVING sumDays < DATEDIFF(...))。

由于您还希望在整个期间都没有预订的客户，我建议从表开始clients并“仅” LEFT JOIN（有效）carings：

  SELECT cl.id, cl.name, IFNULL (SUM (eca.effectiveDays), 0) AS `sumDays`
    FROM clients cl
         LEFT JOIN
         (SELECT ca.id,
                 -- Limit start/end dates to period of interest, respectively
                 GREATEST (ca.startDate, '2017-05-16') AS `effectiveStartDate`,
                 LEAST (ca.endDate, '2017-05-29') AS `effectiveEndDate`,
                 DATEDIFF (
                    DATE_ADD (LEAST (ca.endDate, '2017-05-29'), INTERVAL 1 DAY),
                    GREATEST (ca.startDate, '2017-05-16'))
                    AS `effectiveDays`,
                 ca.clientId
            FROM carings ca
           WHERE ca.startDate <= '2017-05-29' AND ca.endDate >= '2017-05-16')
         eca                                               -- effectiveCarings
            ON eca.clientId = cl.id
GROUP BY cl.id, cl.name
  HAVING sumDays <
            DATEDIFF (DATE_ADD ('2017-05-29', INTERVAL 1 DAY), '2017-05-16')
ORDER BY cl.id;

另请参阅http://sqlfiddle.com/#!9/1038b9/19