LINQ to SQL: GroupBy() and Max() to get the object with latest date

Question

Consider a SQL Server table that\'s used to store events for auditing.

The need is to get only that latest entry for each CustID. We want to get the entire

Answer 1

Here: this uses max rather than OrderByDesc, so should be more efficient.

var subquery = from c in CustAccesses
            group c by c.CustID into g
            select new
            {
                CustID = g.Key,
                AccessDate = g.Max(a => a.AccessDate)
            };
var query = from c in CustAccesses
            join s in subquery 
              on c.CustID equals s.CustID
            where c.AccessDate == s.AccessDate
             && !string.IsNullOrEmpty(c.AccessReason)
            select c;