static void Main()
{
//селектира от таблицата това, което е с ID=1
using (var db = new TelerikAcademyEntities())
{
var project = db.Projects
.Where(pr => pr.ProjectID == 1)
.FirstOrDefault();
Console.WriteLine(project.Name);
var projectCount = db.Projects.ToList();
Console.WriteLine(projectCount.Count);
}
using (var db = new TelerikAcademyEntities())
{
var project = db.Projects.Find(2);
Console.WriteLine(project);
}
//Create, Update, Delete using Entity Framework
//Add
using (var db = new TelerikAcademyEntities())
{
var town = new Town
{
Name = "London"
};
var address = new Address
{
AddressText = "Mladost 4",
Town = town
};
//db.Towns.Add(town);
db.Addresses.Add(address);
db.SaveChanges();
}
//Delete
using (var db = new TelerikAcademyEntities())
{
//Add some town
var town = new Town
{
Name = "Town going to be deleted"
};
db.Towns.Add(town);
db.SaveChanges();
//Remove
var townToDelete = db.Towns.Where(t => t.Name.Contains("deleted")).FirstOrDefault();
db.Towns.Remove(townToDelete);
db.SaveChanges();
}
//view all information - бърз начин с .Select(t => new {..}), което прави
//една заявка с join и е много по-добре от към performance
using (var db = new TelerikAcademyEntities())
{
var towns = db.Towns
.Where(t => t.Addresses.Any())
.Select(t => new
{
t.Name,
Addresses = t.Addresses.Select(a => a.AddressText)
})
.ToList();
foreach (var town in towns)
{
Console.WriteLine(town.Name);
foreach (var address in town.Addresses)
{
Console.WriteLine(address);
}
Console.WriteLine("-----------------------");
}
}
//view all information - тромав начин прави много заявки и прави същото, като горната заявкабн
using (var db = new TelerikAcademyEntities())
{
var towns = db.Towns.Where(t => t.Addresses.Any()).ToList();
Console.WriteLine(towns.Count);
foreach (var town in towns)
{
Console.WriteLine(town.Name);
var addresses = town.Addresses;
foreach (var address in addresses)
{
Console.WriteLine(address.AddressText);
}
Console.WriteLine("-----------------------");
}
}
//use Extended partial class, to add new functionallity
using (var db = new TelerikAcademyEntities())
{
var employee = db.Employees.ToList().Select(e => e.FullName);
foreach (var empl in employee)
{
Console.WriteLine(empl);
}
}
var dbo = new TelerikAcademyEntities();
//Executing Native SQL Queries
var empls = dbo.Database.SqlQuery(typeof(Project), "SELECT * FROM dbo.Projects");
//Joining Tables in EF
//чрез анонимен обект
dbo.Towns
.Select(t => new
{
Name = t.Name,
Address = t.Addresses.Select(a => a.AddressText)
});
//или може да е мапнат към конкретен клас
var result = dbo.Towns
.Select(t => new TownDataModel
{
Name = t.Name,
Address = t.Addresses.Select(a => a.AddressText)
});
Console.WriteLine(result);
//when we use JOIN
var secondResult = dbo.Towns
.Join(
dbo.Addresses,
t => t.TownID, a => a.TownID,
(t, a) => new
{
TownName = t.Name,
AddressTexts = a.AddressText
})
.ToList();
//Join with linq
var employe = dbo.Employees
.Select(e => new
{
FullName = e.FirstName + " " + e.LastName,
Town = e.Address.Town.Name,
Address = e.Address.AddressText,
Project = e.Projects.Select(pr => pr.Name).FirstOrDefault(),
Department = e.Department.Name
});
Console.WriteLine(employe);
//Group
var emplGroups = dbo.Employees
.GroupBy(e => e.Department.Name)
.ToList();
foreach (var empplGr in emplGroups)
{
Console.WriteLine(empplGr.Key);
foreach (var emp in empplGr)
{
Console.WriteLine(emp.FirstName);
}
Console.WriteLine("============================");
}
//Groupby more than 1 thing
var emplsGroups = dbo.Employees
.GroupBy(e => new { e.Department.Name, TownName = e.Address.Town.Name })
.ToList();
//UPDATE
// за целта трябва да се ползва оригиналния обект
var updateEmpl = dbo.Employees.FirstOrDefault();
//може да правим колкото искаме промени
updateEmpl.FirstName = "Pesho";
dbo.SaveChanges();
//Attaching Detached Objects
var em = dbo.Employees.FirstOrDefault();
var dbEntry = dbo.Entry(em);
//нов обект, токущо добавен
dbEntry.State = EntityState.Added;
//изтрии този обект
dbEntry.State = EntityState.Deleted;
//спри да се занимаваш с този обект
dbEntry.State = EntityState.Detached;
//променен този обект
dbEntry.State = EntityState.Modified;
//непроменен обект, скипни промените и го следи отново
dbEntry.State = EntityState.Unchanged;
dbo.SaveChanges();
//Attaching - ръчно
//ако имаме праймъри кй, то тогава променяме наличното в базата
//ако нямаме добавяме нов обект
var e = new Employee
{
EmployeeID = 5,
JobTitle = "Dev"
};
dbo.Employees.Attach(e);
}
