Question

I have a table I am trying to generate reports from.
Its basically a log of when something breaks (goes down), and then gets fixed.

Table schema and some example data is below.
To illustrate:
1 row is inserted when it goes down
1 row is inserted when it comes back up.

What I am trying to do is report on various aspects, things like:
Amount of downtime in a given day / week / month
Number of times its gone down in a given day / week / month.

Ideally in a way that would easily be exported to excel or something similar to be graphed.

I’m having trouble coming up with any kind of queries to get this info.

I have this one for example:

SELECT [Name], datepart(day,[Inserted]), count([SystemDown])     
FROM [DownTimeLog]
WHERE [SystemDown]=1
GROUP BY [Name],datepart(day,[Inserted]) 

which gives me the number of times the system has gone down per day, which is a good starting point.

But i’m trying to come up with a way of showing the total time its been down, but I am drawing a blank.
Some days for example may be 0, sometimes it may go down a few times, so trying to sum the time difference between 2 corresponding rows is provinh tough.

CREATE TABLE [dbo].[DownTimeLog]
(
    [ID] [int] IDENTITY(1,1) NOT NULL,
    [Name] VARCHAR(30) NOT NULL,
    [SystemDown] BIT NOT NULL,
    [Inserted] DATETIME NOT NULL
)

INSERT INTO [DownTimeLog] ([Name],[SystemDown],[Inserted])VALUES('System1',1,'Jun 14 2011  1:49:58:000PM')
INSERT INTO [DownTimeLog] ([Name],[SystemDown],[Inserted])VALUES('System1',0,'Jun 14 2011  2:49:58:000PM')
INSERT INTO [DownTimeLog] ([Name],[SystemDown],[Inserted])VALUES('System1',1,'Jun 15 2011  1:00:00:000PM')
INSERT INTO [DownTimeLog] ([Name],[SystemDown],[Inserted])VALUES('System1',0,'Jun 15 2011  2:00:00:000PM')
INSERT INTO [DownTimeLog] ([Name],[SystemDown],[Inserted])VALUES('System1',1,'Jun 15 2011  4:00:00:000PM')
INSERT INTO [DownTimeLog] ([Name],[SystemDown],[Inserted])VALUES('System1',0,'Jun 15 2011  5:00:00:000PM')
INSERT INTO [DownTimeLog] ([Name],[SystemDown],[Inserted])VALUES('System1',1,'Jun 17 2011  1:00:00:000PM')
INSERT INTO [DownTimeLog] ([Name],[SystemDown],[Inserted])VALUES('System1',0,'Jun 17 2011  3:00:00:000PM')
INSERT INTO [DownTimeLog] ([Name],[SystemDown],[Inserted])VALUES('System1',1,'Jun 18 2011 10:00:00:000AM')
INSERT INTO [DownTimeLog] ([Name],[SystemDown],[Inserted])VALUES('System1',0,'Jun 18 2011 11:00:00:000AM')
INSERT INTO [DownTimeLog] ([Name],[SystemDown],[Inserted])VALUES('System1',1,'Jun 18 2011  1:00:00:000PM')
INSERT INTO [DownTimeLog] ([Name],[SystemDown],[Inserted])VALUES('System1',0,'Jun 18 2011  3:30:00:000PM')
INSERT INTO [DownTimeLog] ([Name],[SystemDown],[Inserted])VALUES('System1',1,'Jun 18 2011  4:00:00:000PM')
INSERT INTO [DownTimeLog] ([Name],[SystemDown],[Inserted])VALUES('System1',0,'Jun 18 2011  8:00:00:000PM')

So for example using the data above I’d like to pull data back that was something like:

System1 | June 14 2011 | 1 hour | 1 occurence
System1 | June 15 2011 | 2 hours | 2 occurence’s
System1 | June 16 2011 | 0 hours | 0 occurence’s
System1 | June 17 2011 | 2 hours | 1 occurence
System1 | June 18 2011 | 7.5 hours | 3 occurence’s

I hope someone can give me a method of doing what I am trying to do.

—
Edit:

Thanks all for some great answers. Helped me out a tonne.
I thought my sql was pretty string, never heard of a cross apply though – guess i need to go back to school!

Cheers!

Answer 1

The following will produce your exact output including missing days. Note, this code is based on Mikael Eriksson’s answer.

CREATE TABLE #DownTimeLog
(
    [ID] [int] IDENTITY(1,1) NOT NULL,
    [Name] VARCHAR(30) NOT NULL,
    [SystemDown] BIT NOT NULL,
    [Inserted] DATETIME NOT NULL
)

INSERT INTO #DownTimeLog ([Name],[SystemDown],[Inserted])VALUES('System1',1,'Jun 14 2011  1:49:58:000PM')
INSERT INTO #DownTimeLog ([Name],[SystemDown],[Inserted])VALUES('System1',0,'Jun 14 2011  2:49:58:000PM')
INSERT INTO #DownTimeLog ([Name],[SystemDown],[Inserted])VALUES('System1',1,'Jun 15 2011  1:00:00:000PM')
INSERT INTO #DownTimeLog ([Name],[SystemDown],[Inserted])VALUES('System1',0,'Jun 15 2011  2:00:00:000PM')
INSERT INTO #DownTimeLog ([Name],[SystemDown],[Inserted])VALUES('System1',1,'Jun 15 2011  4:00:00:000PM')
INSERT INTO #DownTimeLog ([Name],[SystemDown],[Inserted])VALUES('System1',0,'Jun 15 2011  5:00:00:000PM')
INSERT INTO #DownTimeLog ([Name],[SystemDown],[Inserted])VALUES('System1',1,'Jun 17 2011  1:00:00:000PM')
INSERT INTO #DownTimeLog ([Name],[SystemDown],[Inserted])VALUES('System1',0,'Jun 17 2011  3:00:00:000PM')
INSERT INTO #DownTimeLog ([Name],[SystemDown],[Inserted])VALUES('System1',1,'Jun 18 2011 10:00:00:000AM')
INSERT INTO #DownTimeLog ([Name],[SystemDown],[Inserted])VALUES('System1',0,'Jun 18 2011 11:00:00:000AM')
INSERT INTO #DownTimeLog ([Name],[SystemDown],[Inserted])VALUES('System1',1,'Jun 18 2011  1:00:00:000PM')
INSERT INTO #DownTimeLog ([Name],[SystemDown],[Inserted])VALUES('System1',0,'Jun 18 2011  3:30:00:000PM')
INSERT INTO #DownTimeLog ([Name],[SystemDown],[Inserted])VALUES('System1',1,'Jun 18 2011  4:00:00:000PM')
INSERT INTO #DownTimeLog ([Name],[SystemDown],[Inserted])VALUES('System1',0,'Jun 18 2011  8:00:00:000PM')

CREATE TABLE #DownTimeLogModified (Name nvarchar(512), [Date] nvarchar(512), DownTime int,  Occurrences int)

INSERT INTO #DownTimeLogModified (Name, [Date], DownTime,  Occurrences)
select D1.Name,
       CONVERT(VARCHAR(12), dateadd(d, datediff(d, 0, D1.Inserted), 0), 107) as [Date],
       sum(datediff(mi, D1.Inserted, D2.Inserted)) as DownTime,
       count(*) as Occurrences
from #DownTimeLog as D1
  cross apply ( select top 1 Name,
                             Inserted
                from #DownTimeLog
                where SystemDown = 0 and
                      Name = D1.Name and
                      Inserted > D1.Inserted 
                order by Inserted             
              ) as D2
where D1.SystemDown = 1
group by D1.Name, dateadd(d, datediff(d, 0, D1.Inserted), 0)

DECLARE @startdate datetime,@enddate datetime
select @startdate = MIN(Inserted) FROM #DownTimeLog
select @enddate = MAX(Inserted) FROM #DownTimeLog

;WITH DateIntervalsCTE AS
        (
        SELECT 1 i,@startdate AS Date
        UNION ALL
        SELECT i + 1, DATEADD(day, i, @startdate )
        FROM DateIntervalsCTE 
        WHERE DATEADD(day, i, @startdate ) <= @enddate
        )

SELECT CASE WHEN a.Name is null THEN 'No System downtime' ELSE a.Name END as Name,CONVERT(VARCHAR(12), b.Date, 107) AS Date,CASE WHEN a.DownTime is null THEN 0 ELSE a.DownTime END AS DownTime,CASE WHEN a.Occurrences is null THEN 0 ELSE a.Occurrences END AS Occurrences 
FROM DateIntervalsCTE b
LEFT JOIN #DownTimeLogModified a ON a.Date = CONVERT(VARCHAR(12), b.Date, 107)

DROP TABLE #DownTimeLog
DROP TABLE #DownTimeLogModified

Output

Name                           Date                    DownTime    Occurrences
------------------------------ ----------------------- ----------- -----------
System1                        Jun 14, 2011                60           1
System1                        Jun 15, 2011               120           2
No system downtime             Jun 16, 2011                 0           0
System1                        Jun 17, 2011               120           1
System1                        Jun 18, 2011               450           3