DATEADD function is not bringing the correct data SQL Server

Question

I have a float datatype that is actually a date. I need to use it in the condition to obtain the data for the last 10 minutes. I used CAST to convert from float to datetime. and then DATEADD to collect the last 10 minutes data but its not working.

select  CAST(StartTime AS DATETIME) as StartTime
        ,CAST(endtime AS DATETIME) as EndTime
from    BIORADFM_TASK_AUDIT
where   CAST(StartTime AS DATETIME) >= DATEADD(minute, 10, GETDATE());

Result:

StartTime                EndTime
-----------------------  -----------------------
2017-10-12 16:57:06.997  2017-10-12 16:57:06.997
2017-10-12 06:06:59.997  2017-10-12 06:06:59.997
2017-10-12 06:06:47.997  2017-10-12 06:06:47.997
2017-10-11 16:04:53.000  2017-10-11 16:04:53.000

It´s showing data for the next two days, instead of the last 10 minutes starting from getdate.

Table Structure:
CREATE TABLE [dbo].[BIORADFM_TASK_AUDIT](
[STRGUID] [nvarchar](32) NOT NULL,
[ACTIVITYUSERID] [int] NOT NULL,
[ACTIVITYSESSIONID] [int] NOT NULL,
[ACTIVITYCODE] [int] NOT NULL,
[SERVERNAME] [nvarchar](256) NOT NULL,
[APPNAME] [nvarchar](20) NOT NULL,
[STARTTIME] [float] NOT NULL,
[ENDTIME] [float] NOT NULL,
[STRDESCRIPTION] [nvarchar](1000) NULL,
[STRMODULENAME] [nvarchar](300) NULL,
CONSTRAINT [PK_BIORADFM_TASK_AUDIT] PRIMARY KEY CLUSTERED 

Sample Data:

StartTime           Endtime
43020.2549421296    43020.2549421296
43020.2550810185    43020.2550810185
43020.6342939815    43020.6342939815
43020.2548032407    43020.2548032407
43020.2548263889    43020.2548263889
43020.2549421296    43020.2549421296
43020.2549305556    43020.2549305556
43020.2549421296    43020.2549421296
43019.2549189815    43019.2549189815

Answer 1

Don't use datediff() . It counts the number of "time boundaries" between two date/times.

Instead, use date arithmetic:

WHERE A.ActivityUserID = B.lUserID and 
      CAST(A.StartTime AS DATETIME) >= DATEADD(minute, -10, GETDATE())

Answer 2

Just a wild guess since we have nothing to work with. It would be a good idea to store datetime data as datetime instead of a strings so you don't have to constantly convert your data to the right datatype.

SELECT A.strGUID
    , u.sUserName
    , A.ServerName
    , A.AppName
    , A.ActivityCode
    , CAST(A.StartTime AS DATETIME) as StartTime
    , CAST(A.endtime AS DATETIME) as EndTime
    , A.strModuleName
    , A.strDescription
    , GETDATE()
FROM INTRAWPROD_TASK_AUDIT A
join HSV_ACTIVITY_USERS u on A.ActivityUserID = u.lUserID 
where convert(datetime, a.StartTime) >= convert(datetime, dateadd(minute, -10, GETDATE()))

Answer 3

If you want rows with an start time situated only in the last 10 minutes you have to filter by range, for example with BETWEEN :

SELECT CAST(StartTime AS DATETIME) AS StartTime, CAST(endtime AS DATETIME) AS EndTime
FROM BIORADFM_TASK_AUDIT
WHERE CAST(StartTime AS DATETIME) BETWEEN DATEADD(minute,-10,GETDATE()) AND GETDATE()