private static void InsertData()
{
var cars = ProcessCars("fuel.csv");
var db = new CardDb();
if (!db.Cars.Any())
{
foreach (var car in cars)
{
db.Cars.Add(car);
}
db.SaveChanges();
}
}
private static void QueryData()
{
var db = new CardDb();
// this is a query that you'd expect to have trouble with
// because it calls on heirachical resluts, which is not something SQL Does
// but EntityFW can accomodate with a complex SQL query
// it has to do so in order to give them back in a way that works well in C#
db.Database.Log = Console.WriteLine;
var query =
db.Cars.GroupBy(c => c.Manufacturer)
.Select(g => new
{
Name = g.Key,
Cars = g.OrderByDescending(c => c.Combined).Take(2)
});
// same thing with query syntax
var query2 =
from car in db.Cars
group car by car.Manufacturer into manufacturer
select new
{
Name = manufacturer.Key,
Cars = (from car in manufacturer
orderby car.Combined descending
select car).Take(2)
};
foreach (var group in query2)
{
Console.WriteLine(group.Name);
foreach (var car in group.Cars)
{
Console.WriteLine($"\t{car.Name} : {car.Combined}");
}
}
}
