SQL Server Date Functions

var year = 2017;
var month = 2;

var query = DbContext.Set<GrossSalesByDay>()
    .Query((Orders orders, OrderItems orderItems, GrossSalesByDay alias) =>
    {
        var grossSales = SUM(orderItems.ListPrice * orderItems.Quantity);
        var shippedDay = orders.ShippedDate?.Day;

        var r = SELECT<GrossSalesByDay>(shippedDay.@as(alias.Day),
            grossSales.@as(alias.GrossSales));

        FROM(orders).JOIN(orderItems).ON(orderItems.Order == orders);
        WHERE(orders.ShippedDate != null &&
              orders.ShippedDate?.Year == year &&
              MONTH(orders.ShippedDate) == month);
        GROUP(BY(shippedDay));

        return r;
    })
    .OrderBy(gs => gs.Day);

foreach (var grossSalesByDay in query.Take(3))
    Console.WriteLine((grossSalesByDay.Day, grossSalesByDay.GrossSales));