Update previous row, get value from other row - sql-server

Question

I'm very new with T-SQL and I need some help. I have a table1. How I can do this process?
Should I use nested cursor or what? Need an advice on this.
Pls refer pic here -- http://i.stack.imgur.com/CHYIg.gif
Here is my code so far:
DECLARE #get_invckey datetime;
SET #get_invckey = '2013-04-09 13:30:43.537'
UPDATE table1
SET RUNTIME = #get_invckey
FROM
(
SELECT
DCREPORTTIME
FROM table1
WHERE
LOCATIONAME = 'MYQ01_PRNT_A_SP3'
AND EVENT LIKE '%RUN%'
) newdata
WHERE
LOCATIONAME = 'MYQ01_PRNT_A_SP3'
AND EVENT = 'MACHINE B STOPPED'

Answer 1

Not complete answer, for you question is not complex enough.
Just quick and simple example how this could be achieved.
Some sample data
DECLARE #Table table
( dcreporttime datetime, event_name varchar(55))
insert INTO #Table
SELECT '2013-04-09 13:34:01', 'RUNNING'
union
SELECT '2013-04-09 13:34:19', 'STOPPED'
union
SELECT '2013-04-09 13:34:29', 'RUNNING'
union
SELECT '2013-04-09 13:34:39', 'RUNNING'
union
SELECT '2013-04-09 13:35:19', 'STOPPED'
union
SELECT '2013-04-09 13:35:29', 'RUNNING'
union
SELECT '2013-04-09 13:35:39', 'RUNNING'
union
SELECT '2013-04-09 13:36:19', 'RUNNING'
union
SELECT '2013-04-09 13:37:19', 'STOPPED'
union
SELECT '2013-04-09 13:37:39', 'RUNNING'
And the query. It uses CTE (Common Table Expression) and Ranking functions:
;with cte as
(
SELECT RANK() OVER(ORDER by dcreporttime) as RankN, *
FROM #Table
)
select a.dcreporttime, a.event_name, a.dcreporttime, b.dcreporttime, DATEDIFF(ms, a.dcreporttime, b.dcreporttime) as runtime
from cte a
-- shift by Rank to compare with previous row
join cte b on a.RankN = b.RankN + 1
This simply you get time since previous event. I hope this could point you to solution. If don't, please be more specific in what you need :)

Answer 2

I have updated the view as follows:
create view [dbo].[cm] as
WITH cteMain
AS
(SELECT DCREPORTTIME,
ROW_NUMBER() OVER (ORDER BY DCREPORTTIME) AS rn,
RUNTIME,
[EVENT] AS EVENT
FROM
table1),
cte2 as (SELECT
sLeg.rn,
slead.DCREPORTTIME AS leadvalue,
sLeg.DCREPORTTIME AS lagvalue,
m.EVENT
FROM
cteMain AS m
LEFT OUTER JOIN cteMain AS sLead
ON sLead.rn = m.rn+1
LEFT OUTER JOIN cteMain AS sLeg
ON sLeg.rn = m.rn-1)
SELECT cte2.leadvalue, cte2.lagvalue, cte2.rn, cte2.EVENT
FROM cte2
Then, I revised the update query to:
update table1
set RUNTIME = DATEDIFF(ms, lagvalue, leadvalue)
FROM cm
where leadvalue=table1.DCREPORTTIME
and table1.EVENT='MACHINE RUNNING'
I used the first three rows of yours as sample data and this is what I see after the UPDATE:
Is this what you are looking for? I realize, by the way, that this can all be done without a view, but, I found this to be easier to work with, as far as taking on the problem step by step.
I based my query on a query I found at the following link:
Query to simulate Lead function in SQL Server 2008
See SQLFiddle at: SQLFiddle for Update previous row, get value from other row