public void Aggregate_Null()
{
//TODO:
employees.Select("FirstName").Min();
employees.Min("FirstName");
employees.Select("FirstName").Max();
employees.Max("FirstName");
products.Count(o => o.UnitPrice < 1000);
products.Count("UnitPrice < 1000");
products.Average("ProductID");
products.Sum("ProductID");
employees.Select(o => o.FirstName).Min();
employees.Min(o => o.FirstName);
}