Tracking changes in a SQL database - sql-server

Question

I've spent plenty of time Googling and have found possible solutions to much simpler tables.
My company uses BGInfo religiously to keep track of ~80 properties on over 200 web servers. Those fields are a mix of server stats (IP address, OSVer, HyperV host) and versions of various installed software components. A scheduled task writes this information every day all web servers to a single database (currently >300K records). We need a query (to eventually be fed into a report) to give us a time of when something has changed on any given web server. A sort of automated change control if you will.
Example: WebSvr_XYZ used had 2G of RAM since inception before getting additional RAM allocated a few months later. Then a year after that, it was given a new IP address.
Server Time_stamp Host IP RAM
-------------------------------------------------------
WebSvr_XYZ June 1, 2016 Virt5a 192.168.10.45 2G
WebSvr_XYZ June 2, 2016 Virt5a 192.168.10.45 2G
WebSvr_XYZ Aug 20, 2016 Virt5a 192.168.10.45 4G
WebSvr_XYZ Aug 21, 2016 Virt5a 192.168.10.45 4G
WebSvr_XYZ July 18, 2017 Virt5a 192.168.20.105 4G
WebSvr_XYZ July 19, 2017 Virt5a 192.168.20.105 4G
WebSvr_XYZ July 20, 2017 Virt5a 192.168.20.105 4G
When running against WebSvr_XYZ, the output against over 540 records would be
June 1, 2016 Virt5a 192.168.10.45 2G
Aug 20, 2016 Virt5a 192.168.10.45 4G
July 18, 2017 Virt5a 192.168.20.105 4G
I’ve tried the select distinct against the table them Joining it against the full table, joining on all relevant columns and using a MIN(Timestamp) to get the first. But I either get bad timestamps or no results at all.

Answer 1

use row_number() as a sequence of event. After that you can INNER JOIN back itself data of comparing previous timestamp with current timestamp
; with cte as
(
select *, rn = row_number() over (partition by Server order by Time_stamp)
from yourtable
)
select *
from cte c1
inner join c2 on c1.Server = c2.Server
and c1.rn = c2.rn - 1
where c1.IP <> c2.IP
or c1.RAM <> c2.RAM