C#. Entity. CodeSecondApproach

If db already exists and filled with data we just can create Entities in code…

For example lets create db manually… in localdb of SQL Server

View->Server Explorer.

Connect to Database in Visual Studio

Next in serverName type “(localdb)\MSSQLLocalDB” for vs 2015 and choose new datebase or type new one and vs will suggest create new one

Next lets get connection string of our new db in localdb

Data Source=(localdb)\MSSQLLocalDB;Initial Catalog=someNewDB;Integrated Security=True

1	Data Source=(localdb)\MSSQLLocalDB;Initial Catalog=someNewDB;Integrated Security=True

Now put connection string to app.config

<connectionStrings>
<add name="localdb_usersstoredb" connectionString="Data Source=(localdb)\MSSQLLocalDB;Initial Catalog=someNewDB;Integrated Security=True"  providerName="System.Data.SqlClient"/>  
<add name="localdb" connectionString="data source=(localdb)\MSSQLLocalDB;Initial Catalog=userstore.mdf;Integrated Security=True;"  providerName="System.Data.SqlClient"/>
<add name="localdb_usersstoredb" connectionString="data source=(localdb)\MSSQLLocalDB;Initial Catalog=userstoredb;Integrated Security=True;"  providerName="System.Data.SqlClient"/>
</connectionStrings>

</connectionStrings>

Now create new table

and add columns

Click Update and see

Update DataBase and start Editing some data

Now SolutionExplorer > Manage NuGetPackages for Solution > type Entity in search box and Install it to your project

Добавление Entity Framework через NuGet

Установка Entity Framework

Add using System.Data.Entity if not added before…

Lets write user class and userContext class

    public class User
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
    }

    class UserContext : DbContext
    {
        public UserContext() :
            base("localdb_usersstoredb")
        { }

        public DbSet<User> Users { get; set; }
    }

public class User

{

public int Id { get; set; }

public string Name { get; set; }

public int Age { get; set; }

}

class UserContext : DbContext

{

public UserContext() :

base("localdb_usersstoredb")

{ }

public DbSet<User> Users { get; set; }

}

In main lets check what is in our dataBase

    class Program
    {
        static void Main(string[] args)
        {

            using (UserContext db = new UserContext())
            {
                var users = db.Users;               
                foreach (User u in users)
                {
                    Console.WriteLine("{0}.{1} - {2}", u.Id, u.Name, u.Age);
                }
                
            }
            Console.Read();

        }
    }

class Program

{

static void Main(string[] args)

{

using (UserContext db = new UserContext())

{

var users = db.Users;

foreach (User u in users)

{

Console.WriteLine("{0}.{1} - {2}", u.Id, u.Name, u.Age);

}

Console.Read();

}

Full code is

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data.Entity;

namespace CodeSecond
{
    class Program
    {
        static void Main(string[] args)
        {

            using (UserContext db = new UserContext())
            {
                var users = db.Users;               
                foreach (User u in users)
                {
                    Console.WriteLine("{0}.{1} - {2}", u.Id, u.Name, u.Age);
                }
                
            }
            Console.Read();

        }
    }

    public class User
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int Age { get; set; }
    }

    class UserContext : DbContext
    {
        public UserContext() :
            base("localdb_usersstoredb")
        { }

        public DbSet<User> Users { get; set; }
    }

}

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Data.Entity;

namespace CodeSecond

{