Entity Framework: Efficiently grouping by month

Question

I\'ve done a bit of research on this, and the best I\'ve found so far is to use an Asenumerable on the whole dataset, so that the filtering occurs in linq to objects rather

Answer 1

When it comes to group by month i prefer to do this task in this way:

var sqlMinDate = (DateTime) SqlDateTime.MinValue;

var trendData = ExpenseItemsViewableDirect
    .GroupBy(x => SqlFunctions.DateAdd("month", SqlFunctions.DateDiff("month", sqlMinDate, x.Er_Approved_Date), sqlMinDate))
    .Select(x => new
    {
        Period = g.Key // DateTime type
    })

As it keeps datetime type in the grouping result.