max date record in LINQ

Question

I have this table named sample with these values in MS Sql Server:

 ID    Date    Description 1    2012/01/02 5:12:43    Desc1 2    2012/01/02 5:12:48    Desc2 3    2012/01/03 5:12:41    Desc3 4    2012/01/03 5:12:43    Desc4 

Now I want to write LINQ query that result will be this:

4    2012/01/03 5:12:43    Desc4 

I wrote this but it doesn't work:

List<Sample> q = (from n in  Sample.Max(T=>T.Date)).ToList(); 

Answer 1

Starting from .NET 6 MaxBy LINQ method is available.

var result = items.MaxBy(i => i.Date); 

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Prior to .NET 6:

O(n log n):

var result = items.OrderByDescending(i => i.Date).First(); 

O(n) – but iterates over the sequence twice:

var max = items.Max(i => i.Date); var result = items.First(i => i.Date == max); 

Or you can use MoreLINQ which has MaxBy method which is O(n)

Answer 2

To get the maximum Sample value by date without having to sort (which is not really necessary to just get the maximum):

var maxSample  = Samples.Where(s => s.Date == Samples.Max(x => x.Date))                         .FirstOrDefault();