-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
You don't say what time part (days, months, years, hours, minutes,
seconds) you want returned. My example will show hours.
SELECT NodeID, LineStation, MessageFlag, UTC_Time,
DateDiff(Hour, (SELECT MAX(UTC_Time) FROM table_name
WHERE NodeID=T.NodeID AND LineStation=T.LineStation
AND UTC_Time < T.UTC_Time),
UTC_Time) As HoursInterval
FROM table_name As T
WHERE .... < your criteria > ...
ORDER BY NoteID, LineStation, UTC_Time
The "table_name" in both the main query & the subquery should be the
same.
Your data implies that the LineStation is receiving a message
(MessageFlag) at specified times (UTC_TIME). Therefore, I set up the
query to return info on LineStations on the same NodeID. If you just
want to track messages on the NodeID, no matter the LineStation, then
remove the "AND LineStation=T.LineStation" part of the subquery's
criteria (WHERE clause), and remove the LineStation from the ORDER BY
clause.
See the SQL Server BooksOnLine for more info on DateDiff() function.
--
MGFoster:::mgf00 <at> earthlink <decimal-point> net
Oakland, CA (USA)
-----BEGIN PGP SIGNATURE-----
Version: PGP for Personal Privacy 5.0
Charset: noconv
iQA/AwUBQ7HpM4echKqOuFEgEQJWFgCdEMfPaY7aQPYOL66ZJryJpR 4fTMMAoO0r
WEDMaPHxQiZ352eHx0ER72Ur
=YKsf
-----END PGP SIGNATURE-----
ia***********@gmail.com wrote:
I have a data set like so:
UTC_TIME Timestamp NodeID Message Flag
Line
Station
11/19/2005 10:45:07 1132397107.91 1 3 5 1028
1034
11/3/2005 21:05:35 1131051935.20 2 3 5 1009
1043
11/25/2005 21:12:16 1132953136.59 3 3 5 1037
1049
I added the UTC_TIME column in as aconversion of the unix timestamp in
the TIMESTAMP column.
Keeping things simple and straightforward, I need to be able to
calculate the difference from one record to the next (ordered by
TIMESTAMP or UTC_TIME) and output the result into another column in the
table.
NODEID is the unique id.
First, what is the function to do so if, say, I only wanted to
calculate the difference between 2 records as just a basic SELECT
statement. That way I can answer quick question based on any one or two
NODEID's.
Second, how would I further that to continually calculate (as stated
above)?
WOuld this be a stored procedure? A trigger? A cursor?
I am learning as I go here. Any help is greatly appreciated.
R.