public static void QueryCarsDb()
{
var db = new CarDb();
db.Database.Log = Console.WriteLine;
var query = from car in db.Cars
orderby car.Combined descending, car.Name ascending
select car;
var query2 = db.Cars.OrderByDescending(c => c.Combined).ThenBy(c => c.Name).Take(10);
foreach (var car in query.Take(10))
{
Console.WriteLine($"{car.Name}:\t{car.Combined}");
}
}
private static void QueryData()
{
var db = new CarDb();
db.Database.Log = Console.WriteLine;
//var query = from car in db.Cars
// orderby car.Combined descending, car.Name ascending
// select car;
var query =
db.Cars.OrderByDescending(c => c.Combined)
.ThenBy(c => c.Name);
foreach (var car in query.Take(10))
{
Console.WriteLine($"{car.Name}: {car.Combined}");
}
}
private static void InsertData()
{
var carsi = ProcessCars("fuel.csv");
var db = new CarDb();
//db.Database.Log = Console.WriteLine;//ispise ti log vezan za db u cmd
if (!db.Cars.Any())
{
foreach (var car in carsi)
{
db.Cars.Add(car);
}
db.SaveChanges();
}
}
private static void InsertData()
{
var cars = ProcessCars("fuel.csv");
var db = new CarDb();
db.Database.Log = Console.WriteLine;
if (!db.Cars.Any())
{
foreach (var car in cars)
{
db.Cars.Add(car);
}
db.SaveChanges();
}
}
private static void InsertData()
{
var cars = ProcessCars("fuel.csv");
var db = new CarDb();
//this will log the SQL query that has been sent to the db
db.Database.Log = Console.WriteLine;
if (!db.Cars.Any())
{
foreach (var car in cars)
{
db.Cars.Add(car);
}
db.SaveChanges();
}
}
private static void QueryData()
{
var db = new CarDb();
db.Database.Log = Console.WriteLine;
var query = from car in db.Cars
orderby car.Combined descending, car.Name ascending
select car;
var query2 = db.Cars.Where(c => c.Manufacturer == "BMW")
.OrderByDescending(c => c.Combined)
.ThenBy(c => c.Name)
.Take(10)
.ToList();
var query3 =
db.Cars.GroupBy(c => c.Manufacturer)
.Select(g => new
{
Name = g.Key,
Cars = g.OrderByDescending(c => c.Combined).Take(2)
});
var query4 =
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 query4)
{
Console.WriteLine(group.Name);
foreach (var car in group.Cars)
{
Console.WriteLine($"\t{car.Name} : {car.Combined}");
}
}
}
private static void QueryData()
{
var db = new CarDb();
var query = from car in db.Cars
orderby car.Combined descending, car.Name ascending
select car;
var queryExt =
db.Cars.OrderByDescending(c => c.Combined)
.ThenBy(c => c.Name)
.Take(10);
foreach (var car in queryExt)
{
Console.WriteLine($"{car.Name}: {car.Combined}");
}
Console.ReadLine();
}
private static void QueryData()
{
var db = new CarDb();
db.Database.Log = Console.WriteLine;
var query = from car in db.Cars
orderby car.Combined descending, car.Name ascending
select car;
var query2 =
db.Cars.Where(c => c.Manufacturer == "BMW")
.OrderByDescending(c => c.Combined)
.ThenBy(c => c.Name)
.Take(10)
.ToList();
foreach (var car in query2)
{
Console.WriteLine($"{car.Name}: {car.Combined}");
}
}
//Entity and Linq
private static void QueryData()
{
var db = new CarDb();
//db.Database.Log = Console.WriteLine; not a method on dotnet core
var query = from car in db.Cars
orderby car.Combined descending, car.Name ascending
select car;
foreach (var car in query.Take(10))
{
Console.WriteLine($"{ car.Name}: {car.Combined}");
}
var extentionQuery =
db.Cars.OrderByDescending(c => c.Combined).ThenBy(c => c.Name).Take(10);
foreach (var car in extentionQuery)
{
Console.WriteLine($"{ car.Name}: {car.Combined}");
}
}
//// METHOD SYNTAX
//private static void QueryData() {
// var db = new CarDb();
// db.Database.Log = Console.WriteLine;
// var query =
// db.Cars.GroupBy(c => c.Manufacturer)
// .Select(g => new {
// Name = g.Key,
// Cars = g.OrderByDescending(c => c.Combined).Take(2)
// });
// foreach (var group in query) {
// Console.WriteLine(group.Name);
// foreach (var car in group.Cars) {
// Console.WriteLine($"\t{car.Name}: {car.Combined}");
// }
// }
// //Console.WriteLine(query.Count());
// //foreach (var car in query) {
// // Console.WriteLine($"{car.Name}: {car.Combined}");
// //}
//}
// QUERY SYNTAX
private static void QueryData()
{
var db = new CarDb();
db.Database.Log = Console.WriteLine;
var query = from car in db.Cars
group car by car.Manufacturer into manufacturer
select new {
Name = manufacturer.Key,
Cars = (from car in manufacturer
orderby car.Combined descending
select car).Take(2)
};
foreach (var group in query)
{
Console.WriteLine(group.Name);
foreach (var car in group.Cars)
{
Console.WriteLine($"\t{car.Name}: {car.Combined}");
}
}
}
private static void QueryData()
{
var db = new CarDb();
db.Database.Log = Console.WriteLine; //logs the database log to the console -- a way to check that the information is going to the database without checking the database itself
//----query syntax
var query =
from car in db.Cars
orderby car.Combined descending, car.Name ascending
select car;
//---extension method syntax
//Note that EF will only work with IQueryable types. If the method calls for IEnumerables, it must be done in memory.
/* var queryEx =
* db.Cars.Where(c => c.Manufacturer == "BMW")
* .OrderByDescending(c => c.Combined)
* .ThenBy(c => c.Name)
* // .Take(10)
* // .Select(c => new { Name = c.Name.Split(" ") })
* // .ToList();
* // note how this doesn't work because EF can not understand Split and this works as an IQueryable
* .Take(10)
* .ToList()
* .Select(c => new { Name = c.Name.Split(' ') }); //here we are working in memory and can use methods such as split
*
* foreach (var car in queryEx)
* {
* for (var i = 0; i < car.Name.Length; i++)
* {
* Console.WriteLine($"{car.Name[i]}");
* }
* } */
//-- more complex syntax for EF using Ex. Methods
var query2 =
db.Cars.GroupBy(c => c.Manufacturer)
.Select(g => new
{
Name = g.Key,
Cars = g.OrderByDescending(c => c.Combined).Take(2)
});
//-- executing same code using query syntax
var query3 =
from car in db.Cars
group car by car.Manufacturer into manufacturer
select new
{
Name = manufacturer.Key,
Cars = (from car in manufacturer //can even use query syntax within anon constructor.
orderby car.Combined descending
select car).Take(2)
};
foreach (var group in query3)
{
Console.WriteLine(group.Name);
foreach (var car in group.Cars)
{
Console.WriteLine($"\t{car.Name} : {car.Combined}");
}
}
}
private static void QueryData()
{
var db = new CarDb();
db.Database.Log = Console.WriteLine;
#region Complex
// query syntex
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)
};
// Extention method syntex
var query = db.Cars.GroupBy(c => c.Manufacturer)
.Select(g => new
{
Name = g.Key,
Cars = g.OrderByDescending(c => c.Combined).Take(2)
});
foreach (var group in query2)
{
Console.WriteLine(group.Name);
foreach (var car in group.Cars)
{
Console.WriteLine($"\t {car.Name} : {car.Combined}");
}
}
#endregion
#region Simple
//var query = from car in db.Cars
// orderby car.Combined descending, car.Name
// select (car);
//foreach (var car in query.Take(10))
//{
// Console.WriteLine($"{car.Name} : {car.Combined}");
//}
//var query = db.Cars.Where(c => c.Manufacturer == "BMW")
// .OrderByDescending(c => c.Combined)
// .ThenBy(c => c.Name)
// .Take(10) // without tolist it run on the sql IEnumeramble
// .Select(c=> new {Name = c.Name.ToUpper()})
// .ToList(); // with tolist rum in the memory IQueryable
//foreach (var item in query)
//{
// Console.WriteLine(item.Name);
//}
//foreach (var car in query)
//{
// Console.WriteLine($"{car.Name} : {car.Combined}");
//}
#endregion
}
private static void QueryData()
{
var db = new CarDb();
db.Database.Log = Console.WriteLine;
var query =
from car in db.Cars
group car by car.Manufacturer into manufacturer
select new {
Name = manufacturer.Key,
Cars = (from car in manufacturer
orderby car.Combined descending
select car)
.Take(2)
};
//var query =
// from car in db.Cars
// group car by car.Manufacturer into manufacturer
// select new {
// Name = manufacturer.Key,
// Cars = manufacturer.OrderByDescending(c => c.Combined).Take(2)
// };
//var query = db.Cars
// .GroupBy(c => c.Manufacturer)
// .Select(g => new {
// Name = g.Key,
// Cars = g.OrderByDescending(c => c.Combined).Take(2)
// });
foreach (var group in query)
{
Console.WriteLine(group.Name);
foreach (var car in group.Cars)
{
Console.WriteLine($"\t{car.Name} : {car.Combined}");
}
}
//var query =
// from car in db.Cars
// orderby car.Combined descending, car.Name ascending
// select car;
//var query = db.Cars
// .Where(c => c.Manufacturer == "BMW")
// .OrderByDescending(c => c.Combined)
// .ThenBy(c => c.Name)
// .Take(10)
// .ToList();
//.Select(c => new { Name = c.Name.Split(' ') }); // not supported by entity framework
//foreach (var item in query) {
// Console.WriteLine(item.Name);
//}
//Console.WriteLine(query.Count());
//foreach (var car in query) {
// Console.WriteLine($"{car.Name} : {car.Combined}");
//}
}
