SQL查询来汇总则DateDiff大于给定值
题
我有用于设备“心跳”一个记录表。我的这些网络设备,办理入住手续/每10分钟服务器心跳。我们是想,当他们想念自己的计划入住时间统计。我有一个查询,可以做到这在每个装置的基础上,但我需要它在所有设备进行修改,以手柄。
心跳表看起来像这样:
CREATE TABLE [dbo].[DeviceHeartbeat](
[Id] [int] IDENTITY(1,1) NOT NULL,
[DeviceId] [int] NULL,
[CheckinTime] [datetime] NULL,
[Runtime] [int] NULL,
PRIMARY KEY CLUSTERED
([Id] ASC)) ON [PRIMARY]
设备检查到服务器,服务器会将一行添加到该表中它的ID,该CheckinTime和器件的运行时(由设备发送的硬件值)。 查询我目前看起来是这样的:
WITH t AS
(
SELECT Checkintime, rn = ROW_NUMBER() OVER (ORDER BY Checkintime)
FROM DeviceHeartbeat
WHERE DeviceId = 1112
),
x AS
(
SELECT d = DATEDIFF(MINUTE, t1.Checkintime, t2.Checkintime)
FROM t AS t1
INNER JOIN t AS t2
ON t1.rn = t2.rn - 1
),
y AS
(
SELECT stats = CASE WHEN d < 10 THEN ' < 10 '
WHEN d BETWEEN 10 AND 11 THEN '10 - 11 '
WHEN d BETWEEN 11 AND 12 THEN '11 - 12 '
ELSE '+12 ' END + ' minutes:'
FROM x
)
SELECT stats, COUNT(*) FROM y GROUP BY stats;
此查询限于单个指定的设备。实施例的结果如下所示:
stats
----------------- ----
< 10 minutes: 1536
10 - 11 minutes: 425
11 - 12 minutes: 952
+12 minutes: 160
在理想情况下,我只关注签入超过12分钟以上。所以,我是想是谁拥有签入超过12分钟,他们的罪名下令更大的设备的列表。这将让我看到上面有大于12分钟时检查,10倍或20的设备,提醒我问题的设备。 是这样的:
DeviceId CheckinsOver12Mins
---------- -------------------
1112 160
1108 152
15 114
106 86
建议?
解决方案
尝试这种情况:
WITH t AS
(
SELECT Checkintime, DeviceID, rn = ROW_NUMBER() OVER (ORDER BY DeviceID, Checkintime)
FROM DeviceHeartbeat
),
x AS
(
SELECT t1.deviceID, d = DATEDIFF(MINUTE, t1.Checkintime, t2.Checkintime)
FROM t AS t1
INNER JOIN t AS t2
ON t1.rn = t2.rn - 1 and t1.DeviceID = t2.DeviceID
),
y AS
(
SELECT deviceID
FROM x
WHERE d > 12
)
select deviceID, count(deviceID) as [Checkins over 12 mins] FROM y GROUP BY deviceID
注:没有测试数据 - 没有测试,可能有错别字
应当在y CTE可以去除和改变为使得一个较小的查询:
select deviceID, count(deviceID) as [Checkins over 12 mins]
FROM x
GROUP BY deviceID
HAVING d > 12
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