Entity Framework 5 tutorial (Introduction to Entity framework 5 for beginners)

For this example, I will be accessing a SQL table called person which looks like this

  Id int  

FirstName varchar(MAX)  

LastName varchar(MAX)  

Address varchar(MAX)  

Age int  

I have set the primary key on the id column.

In this example I will first perform a select,update, insert and delete in the old fashioned way using ado.net. Then I will perform the same actions using Entity Framework 5. I will be doing all this in a console application.

CRUD operations using ADO.net

Add this to your console application's app.config inside the configuration element. (Replace appropriate values

  <connectionStrings>
    <add
      name = "ConnString"
      connectionString = "Data Source=myServerName; Initial Catalog=myDatabaseName;Integrated Security=False;User ID=myUserName;Password=myPassword"
      providerName = "System.Data.SqlClient" />
  </connectionStrings>

Add to your project a reference to the System.Configuration.dll

This is how my console application solution looks like

Given below is the code

Program.cs

namespace EntityPlay
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            var dataAccess = new DataAccess();
 
            //select
            Person person = dataAccess.GetPerson(1);
 
            //update (change his age to 60)
            person.Age = 60;
            dataAccess.UpdatePerson(person);
 
            //Insert John Doe 
            var newPerson = new Person {FirstName = "John", LastName = "Doe", Address = "CT", Age = 28};
            dataAccess.InsertPerson(newPerson);
 
            //Delete person with id 5
            dataAccess.DeletePerson(5);
        }
    }
}

Person.cs

namespace EntityPlay
{
    public class Person
    {
        public int Id { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public string Address { get; set; }
        public int Age { get; set; }
    }
}

DataAccess.cs

using System;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
 
namespace EntityPlay
{
    public class DataAccess
    {
        private readonly string _connectionString = ConfigurationManager.ConnectionStrings["ConnString"].ToString();
 
        //SELECT
        public Person GetPerson(int id)
        {
            var person = new Person();
            using (var conn = new SqlConnection(_connectionString))
            {
                string commandText = @"SELECT * FROM Person WHERE Id=" + id;
 
                using (var cmd = new SqlCommand(commandText, conn))
                {
                    cmd.CommandType = CommandType.Text;
                    conn.Open();
                    SqlDataReader reader = cmd.ExecuteReader();
 
                    if (reader.Read())
                    {
                        person.Id = id;
                        person.FirstName = reader["FirstName"].ToString();
                        person.LastName = reader["LastName"].ToString();
                        person.Address = reader["Address"].ToString();
                        person.Age = Int32.Parse(reader["Age"].ToString());
                    }
                }
            }
 
            return person;
        }
 
        //UPDATE
        public void UpdatePerson(Person person)
        {
            using (var conn = new SqlConnection(_connectionString))
            {
                string commandText =
                    String.Format(
                        @"UPDATE Person SET FirstName='{0}', LastName='{1}', Address='{2}', Age={3} WHERE Id={4}",
                        person.FirstName, person.LastName, person.Address, person.Age, person.Id);
 
                using (var cmd = new SqlCommand(commandText, conn))
                {
                    cmd.CommandType = CommandType.Text;
                    conn.Open();
                    cmd.ExecuteNonQuery();
                }
            }
        }
 
        // INSERT
        public void InsertPerson(Person person)
        {
            using (var conn = new SqlConnection(_connectionString))
            {
                string commandText =
                    String.Format(
                        @"INSERT INTO Person (FirstName, LastName, Address, Age) VALUES ('{0}','{1}','{2}',{3})",
                        person.FirstName, person.LastName, person.Address, person.Age);
 
                using (var cmd = new SqlCommand(commandText, conn))
                {
                    cmd.CommandType = CommandType.Text;
                    conn.Open();
                    cmd.ExecuteNonQuery();
                }
            }
        }
 
        //DELETE
        public void DeletePerson(int Id)
        {
            using (var conn = new SqlConnection(_connectionString))
            {
                string commandText = String.Format(@"DELETE FROM PERSON WHERE Id=" + Id);
 
                using (var cmd = new SqlCommand(commandText, conn))
                {
                    cmd.CommandType = CommandType.Text;
                    conn.Open();
                    cmd.ExecuteNonQuery();
                }
            }
        }
    }
}

Now lets see how we can do the same operations doing entity framework

CRUD operations using Entity Framework

Follow these steps

1>Add entity framework 5 to your project using the nuget command

Install-Package EntityFramework -Version 5.0.0

2>Add an entity DataModel (this can be thought of as the code representation of your database)

Select  generate from database in the next screen and click next and follow the instructions. Accept all the default settings. On the screen where we select tables, I just selected the Person table. I set my model namespace as PlayEntities.


This is how my code in the Program.cs looks like now

using System.Linq;
 
namespace EntityPlay
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            Person person;
            using (var context = new PlayEntities())
            {
                //select
                person = context.People.First(p => p.Id == 1);
 
                //Update
                person.Age = 60;
                context.SaveChanges();
            }
 
 
            //Insert John Doe 
            var newPerson = new Person {FirstName = "John", LastName = "Doe", Address = "CT", Age = 28};
            using (var context = new PlayEntities())
            {
                context.People.Add(newPerson);
                context.SaveChanges();
            }
 
 
            //Delete
            using (var context = new PlayEntities())
            {
                Person deletePerson = context.People.First(p => p.Id == newPerson.Id);
                context.People.Remove(deletePerson);
                context.SaveChanges();
            }
        }
    }
}

As you can see, once you set up the DataModel, you just need to work with the model. You don't need to worry about writing the lower level code that actually persists data it into the database.