Returning max version number per interval period timestamp - entity-framework

Question

I have a dataset with the following fields:
IntervalPeriodTimestamp
RegisterTypeCode
ReadingReplacementVersion
IntervalValue
I receive readings every 30 minutes but sometimes these readings are replaced and the readingreplacementversionumber is incremented.
Using LINQ how can I return only a list of the largest reading replacementversion for each half hourly period?
I have tried:
db.IntervalInformations
.Where(ii => ii.ChannelInformation.RegisterTypeCode == "62")
.OrderBy(ii => ii.IntervalPeriodTimestamp)
.ThenBy(ii => ii.ChannelInformation.Meter.messageType342.ReadingReplacementVersionNumber)
.ToList();
This returns a list sorted by Interval Period Timestamp and then by Replacement Version but I only want to return the list of interval informations with the MAX one. I have been able to achieve this in SQL using code:
WITH CTE AS
(
select SerialNumber, RegisterTypeCode, IntervalStatusCode, UOM_Code,
IntervalPeriodTimestamp, ReadingReplacementVersionNumber, IntervalValue,
RN = ROW_NUMBER()
OVER (PARTITION BY IntervalPeriodTimestamp
ORDER BY ReadingReplacementVersionNumber desc)
from MarketMessage as a
inner join messageType342 as b on a.MarketMessageID = b.MarketMessageID
inner join Meter as c on b.messageType342ID = c.MessageType342ID
inner join ChannelInformation as d on c.MeterID = d.MeterID
inner join IntervalInformation as e on d.ChannelInformationID = e.ChannelInformationID
where MPRN = 101010101010
and CAST(IntervalPeriodTimestamp as date) between '1 feb 2018' and '28 feb 2018'
and RegisterTypeCode = 62
)
select * from CTE
WHERE RN = 1
Not sure how I can convert this to LINQ statement

Answer 1

Try something like this: group your items into the different groups from which you want only one record, order the records by ReadingReplacementVersionNumber in descendent order, and get the first record in each group. Easier to understand with some code:
db.IntervalInformations
.Where(ii => ii.ChannelInformation.RegisterTypeCode == "62")
.OrderByDescending(ii => ii.ReadingReplacementVersionNumber )
.GroupBy(x => new { x.SerialNumber, x.RegisterTypeCode, x.IntervalStatusCode })
.Select(g => g.First());
The list of properties in GroupBy in your real query may be different. You have to define correctly the criteria for composing the groups. Include in the GroupBy list the combination of properties that will have the same value in each one of your groups, and different values in other groups.