如何在mysql的between子句中包含null datetime

Question

我尝试在devicetime =＆＃39; 2017-04-06 10：06：57＆＃39;和devicetime =＆＃39; 2017-04-06 10:07:05＆＃39;但结果并不包括具有空值的devicetime。

select * from positions where devicetime between '2017-04-06 10:06:57' and '2017-04-06 10:07:05' and deviceId=2

我在上面尝试了这个查询，但它没有用。

Answer 1

首先，您应该谨慎使用between和datetime值。通常，您希望严格小于上限值。

无论如何，你只是在寻找基本逻辑：

select p.*
from positions p
where (device time is null or
       devicetime between '2017-04-06 10:06:57' and '2017-04-06 10:07:05'
      ) and
      deviceId = 2;

Answer 2

您可以执行以下操作

select * from positions where (devicetime between '2017-04-06 10:06:57' and '2017-04-06 10:07:05' and deviceId=2) or devicetime is null

Answer 3

所以只需添加一个空检查。

for an_array in mylist:

Answer 4

我希望你想要这样的东西，应该在null device device中添加回来（但仍然是deviceId = 2）

select * from positions 
where ((devicetime between '2017-04-06 10:06:57' and '2017-04-06 10:07:05') or  devicetime IS NULL)
and deviceId=2

Answer 5

假设在显示的数据之外还有其他行为NULL，devicetime基于select * from positions where id between ( select MAX(id) from positions where devicetime <= '2017-04-06 10:06:57' ) and ( select MIN(id) from positions where devicetime >= '2017-04-06 10:07:05' ) and deviceId=2 是顺序的：

  ( select id from positions
    where devicetime = '2017-04-06 10:06:57'
  )

如果您知道确切的时间，也可以使用

servertime

或者尝试使用devicetime代替if [ $0 == "test" ] || $0 == "all" ]，这似乎是非空的。

Answer 6

您可以在'2017-04-06 10:06:57'和'2017-04-06 10:07:05'或者devicetime = NULL和deviceId = 2 之间添加设备时间

Answer 7

您也可以执行以下操作

1.第一种方式

while (1) {
    alert("hello, world!");
}

2.第二种方式

SELECT * FROM positions WHERE (devicetime BETWEEN '2017-04-06 10:06:57' AND '2017-04-06 10:07:05' AND deviceId=2) OR (devicetime IS NULL AND deviceId=2)