C# SQL linked database

SQL architecture

//domain

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

namespace domain
{
    public class book
    {
        public int id { get; set; }

        public string title { get; set; }

        public string isbn { get; set; }

        //for SQL secondary key, format has to be xxid, or won't be recogonized as key
        public int Aid { get; set; }      

        public author A { get; set; }
   
    }
}

-----------------------------------------------

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace domain

{

    public class author

    {

        public int id { get; set; }

        public string first_name { get; set; }

        public string last_name { get; set; }

        public IList<book> B { get; set; }

    }

}

---------------------------------------------------

//data

//add Entityframework & domain to reference

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using domain;

using System.Data.Entity;

namespace data

{

    public class data_base:DbContext

    {

        public data_base():base("name = Connection"){ }

        public DbSet<author> As { get; set; }

        public DbSet<book> Bs { get; set; }

    }

}

----------------------------------------------------

//app.config under data

<?xml version="1.0" encoding="utf-8"?>

<configuration>

  <configSections>

    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->

    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />

  </configSections>

  <entityFramework>

    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">

      <parameters>

        <parameter value="mssqllocaldb" />

      </parameters>

    </defaultConnectionFactory>

    <providers>

      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />

    </providers>

  </entityFramework>

<connectionStrings>

   <add connectionString="server=DESKTOP-EUFGQAP;database=XYZ;Trusted_Connection=Yes"

           name="Connection"

           providerName="System.Data.SqlClient"/>

</connectionStrings>

</configuration>

------------------------------------------------------

//business

//add data & domain & entityframework to reference

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace business

{

    public class book_package

    {

        public int id { get; set; }

        public string title { get; set; }

        public int Aid { get; set; }

        public string author_name { get; set; }

    }

}

--------------------------------------------------------

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using data;

using domain;

namespace business

{

    public class manager

    {

        public static List<book_package> get_all()

        {

            var db = new data_base();

            var books = db.Bs.Select(x => new book_package

            {

                id = x.id,

                title = x.title,

                

                Aid = x.Aid,

                author_name = x.A.first_name+" "+x.A.last_name

            }).ToList();

            return books;

        }

    }

}

-----------------------------------------------------

//presentation

//add business & entityframework to reference

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows.Forms;

using business;

namespace presentation

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

            dataGridView1.DataSource = manager.get_all();

        }

    }

}

--------------------------------------------------------

//app config under presentation

//copy from app config under data

<?xml version="1.0" encoding="utf-8"?>

<configuration>

  <configSections>

    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->

    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />

  <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 --></configSections>

  <entityFramework>

    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">

      <parameters>

        <parameter value="mssqllocaldb" />

      </parameters>

    </defaultConnectionFactory>

    <providers>

      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />

    </providers>

  </entityFramework>

  <connectionStrings>

    <add connectionString="server=DESKTOP-EUFGQAP;database=XYZ;Trusted_Connection=Yes" name="Connection" providerName="System.Data.SqlClient" />

  </connectionStrings>

    <startup> 

        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.2" />

    </startup>

</configuration>

-----------------------------------------------------------------------------------

SQL author database

SQL book database

visual studio tablegrid view

-----------------------------------------------------------------

//migration

//use when database table design is changed

//view-> other window -> package manage console

//Enable-Migrations

//Add-Migration Add-Migration AddbooksAid //(format: ADD+database+changed property)

//Update-Database