Use one equality operator for comparison with cyclic retrieval and resolution

If the start time is excluded (by using > instead of >=), then a gap of "resolution" is left at the beginning of the result set. In this case, the first row returned will have the timestamp of the (start date + resolution). If the end date uses "<" then the last row returned will be the last row defined by (start date + N*resolution) which has a timestamp less than the end date.

The row that equates to the time that is designated using the < (or >) operator is not returned.

Query 1

This query uses a resolution of 1000, resulting in a 1 second resolution for the data.. The starting time is set to >=.

SELECT DateTime, Value

FROM History

WHERE TagName = 'SysTimeSec'

AND wwResolution = 1000

AND DateTime >= '2001-01-13 12:00:00'

AND DateTime < '2001-01-13 12:01:00'

The results are:

(60 row(s) affected)

Query 2

This query also uses a row resolution of 1000, resulting in a 1 second resolution for the data. The starting time is set to <=.

SELECT DateTime, Value

FROM History

WHERE TagName = 'SysTimeSec'

AND wwResolution = 1000

AND DateTime > '2001-01-13 12:00:00'

AND DateTime <= '2001-01-13 12:01:00'

The results are:

(60 row(s) affected)