SQL Server : complex query to get average time - sql

Question

I have a complex SQL query please resolve. Here is the details of it.
As I think the screenshot I have attached shows all the requirements. The system works like this.
I am creating a text file in my application and logging the same in SQL Server also. As soon as this file gets created, with same name another file gets created with .html extension. I am logging the html file also in SQL Server. So basically if you want you can group the rows on the basis of file name to get a single request.
Now by using SQL I want to get the time difference between these two files. As you can see in the image that first request has taken 547 milliseconnds.
The same way I want to get the average time taken by all the requests in a minute or hour.
SQL Script
CREATE TABLE [dbo].[DebugInfo](
[Id] [bigint] IDENTITY(1,1) NOT NULL,
[FileName] [varchar](250) NULL,
[Message] [varchar](250) NULL,
[Time] [datetime] NULL,
[UserId] [int] NULL,
CONSTRAINT [PK_DebugInfo] PRIMARY KEY CLUSTERED
(
[Id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
SET IDENTITY_INSERT [dbo].[DebugInfo] ON
INSERT [dbo].[DebugInfo] ([Id], [FileName], [Message], [Time], [UserId]) VALUES (1, N'\\172.16.1.18\datadrive\vol2\SCANNING\SCAN\NovToWin\SIP1\WH000001.txt', N'File Is LOCKED Count:- 511', CAST(0x0000A43300CF83FD AS DateTime), NULL)
INSERT [dbo].[DebugInfo] ([Id], [FileName], [Message], [Time], [UserId]) VALUES (2, N'\\172.16.1.18\datadrive\vol2\SCANNING\SCAN\NovToWin\SIP1\WH000001.htm', N'File Is LOCKED Count:- 335', CAST(0x0000A43300CF84A1 AS DateTime), NULL)
INSERT [dbo].[DebugInfo] ([Id], [FileName], [Message], [Time], [UserId]) VALUES (3, N'\\172.16.1.18\datadrive\vol2\SCANNING\SCAN\NovToWin\SIP1\WH000002.txt', N'File Is LOCKED Count:- 672', CAST(0x0000A43300D0072D AS DateTime), NULL)
INSERT [dbo].[DebugInfo] ([Id], [FileName], [Message], [Time], [UserId]) VALUES (4, N'\\172.16.1.18\datadrive\vol2\SCANNING\SCAN\NovToWin\SIP1\WH000002.htm', N'File Is LOCKED Count:- 1006', CAST(0x0000A43300D00895 AS DateTime), NULL)
INSERT [dbo].[DebugInfo] ([Id], [FileName], [Message], [Time], [UserId]) VALUES (5, N'\\172.16.1.18\datadrive\vol2\SCANNING\SCAN\NovToWin\SIP1\WH000003.txt', N'File Is LOCKED Count:- 254', CAST(0x0000A43300D00FC9 AS DateTime), NULL)
INSERT [dbo].[DebugInfo] ([Id], [FileName], [Message], [Time], [UserId]) VALUES (6, N'\\172.16.1.18\datadrive\vol2\SCANNING\SCAN\NovToWin\SIP1\WH000003.htm', N'File Is LOCKED Count:- 136', CAST(0x0000A43300D01001 AS DateTime), NULL)
INSERT [dbo].[DebugInfo] ([Id], [FileName], [Message], [Time], [UserId]) VALUES (7, N'\\172.16.1.18\datadrive\vol2\SCANNING\SCAN\NovToWin\SIP1\WH000004.txt', N'File Is LOCKED Count:- 772', CAST(0x0000A43300D0167E AS DateTime), NULL)
INSERT [dbo].[DebugInfo] ([Id], [FileName], [Message], [Time], [UserId]) VALUES (8, N'\\172.16.1.18\datadrive\vol2\SCANNING\SCAN\NovToWin\SIP1\WH000004.htm', N'File Is LOCKED Count:- 181', CAST(0x0000A43300D016C5 AS DateTime), NULL)
INSERT [dbo].[DebugInfo] ([Id], [FileName], [Message], [Time], [UserId]) VALUES (9, N'\\172.16.1.18\datadrive\vol2\SCANNING\SCAN\NovToWin\SIP1\WH000005.txt', N'File Is LOCKED Count:- 347', CAST(0x0000A43300D01B65 AS DateTime), NULL)
INSERT [dbo].[DebugInfo] ([Id], [FileName], [Message], [Time], [UserId]) VALUES (10, N'\\172.16.1.18\datadrive\vol2\SCANNING\SCAN\NovToWin\SIP1\WH000005.htm', N'File Is LOCKED Count:- 117', CAST(0x0000A43300D01B8F AS DateTime), NULL)
INSERT [dbo].[DebugInfo] ([Id], [FileName], [Message], [Time], [UserId]) VALUES (11, N'\\172.16.1.18\datadrive\vol2\SCANNING\SCAN\NovToWin\SIP1\WH000006.txt', N'File Is LOCKED Count:- 572', CAST(0x0000A43300F13506 AS DateTime), NULL)
INSERT [dbo].[DebugInfo] ([Id], [FileName], [Message], [Time], [UserId]) VALUES (12, N'\\172.16.1.18\datadrive\vol2\SCANNING\SCAN\NovToWin\SIP1\WH000006.htm', N'File Is LOCKED Count:- 562', CAST(0x0000A43300F13632 AS DateTime), NULL)
Here is what i have used to generate the RawFileName
SELECT *, SUBSTRING((REVERSE
(
SUBSTRING
(
REVERSE(FileName),0,CHARINDEX('\',REVERSE(FileName))
)
)),0, CHARINDEX('.',REVERSE
(
SUBSTRING
(
REVERSE(FileName),0,CHARINDEX('\',REVERSE(FileName))
)
))) AS RawFileName from DebugInfo
Thanks

Answer 1

Does this do what you want?
select avg(diff_ms * 1.0)
from (select datediff(millisecond, min(time), max(time)) as diff_ms
from t
group by rawfilename
) t;

Answer 2

select avg(diff)
from ( select filename, DATEDIFF(MILLISECOND, Time, nextTime) as diff
from ( select [FileName]
, [Time]
, lead(Time, 1, 0) OVER (ORDER BY id) AS nextTime
, row_number() over (partition by FileName order by Time) as rn
from [DebugInfo]
) tt
where tt.rn = 1
) ttt
select avg(diff)
from ( select datediff(millisecond, minTime, maxTime) as diff
from ( select min(time) as minTime, max(time) ss maxTime
from [DebugInfo]
group by rawfilename
) tt
) ttt;