Question

我设计了一个数据库模式来保存患者约会。每小时被分成相等的15个插槽，最后两个插槽在紧急情况下始终保持未使用状态。打印预约列表时，我需要预约所有约会以及14行的空行。每小时第15个位置，因此接待员可以在打印的纸张上手工填写计划外的预约。

appt_schedules：

id
slot_id
hour
scheduled_on

插槽表 - 始终包含15行。

id
start_time
end_time

以下查询给出了预期的结果，除了14＆amp;的空行。第15个插槽。

SELECT `appt_schedules`.* FROM `appt_schedules` 
LEFT JOIN `slots` ON `appt_schedules`.`slot_id` = `slots`.`id` 
WHERE `scheduled_on`='2015-04-17' LIMIT 10,10

我也对模式更改持开放态度，这可以带来简单有效的查询。

Answer 1

SELECT `appt_schedules`.*, `slots`.`slot_id` FROM `appt_schedules` 
LEFT JOIN `slots` ON `appt_schedules`.`slot_id` = `slots`.`id` 
 WHERE `scheduled_on`='2015-04-17'  and `slots`.`slot_id` between 1 and 15

假设cours slots.slot_id将15个相等的alots保持为int 1到15

另一种更优化的写法是：

    SELECT `appt_schedules`.*, `slots`.`slot_id` FROM `appt_schedules` 
    LEFT JOIN `slots` ON `appt_schedules`.`slot_id` = `slots`.`id` 
     WHERE `scheduled_on`='2015-04-17'  and `slots`.`slot_id` IS NOT NULL

甚至更好：

    SELECT `appt_schedules`.*, `slots`.`slot_id` FROM `appt_schedules` 
    JOIN `slots` ON `appt_schedules`.`slot_id` = `slots`.`id` 
     WHERE `scheduled_on`='2015-04-17'

**** BEGIN REVISED EDIT ****

如果我理解正确，请尝试：

 SELECT s.slot_id, aps.* FROM slots s
 LEFT JOIN 
     (SELECT *, ROW_NUMBER() 
             over(PARTITION BY aps.slot_id 
                       ORDER BY aps.slot_id
                     ,aps.scheduled_on)  AS RowId
      FROM appt_schedules aps) aps
         ON aps.slot_id = s.id
            AND s.slot_id = aps.RowId
WHERE scheduled_on = '2015-04-17'
ORDER BY s.slot_id

再次感谢您删除slos.slot_id ....

 select * 
   from slots s 
   left join appt_schedules as 
      on s.id = as.slot_id 
  where IFNULL(as.scheduled_on, '') in ('', '2015-04-17')

为未使用的插槽生成空行

1 个答案: