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Introduction

This article introduces Entity Framework to absolute beginners. The article is meant for developers who are primarily using ADO.NET to write their data access layers. Many experienced developers will find this article very basic but since the article is written from the perspective of beginners, I've tried to keep things simple.

Background

ADO.NET is a very strong framework for data access. ADO.NET has been around since many years and there are a lot of systems running over ADO.NET. Developers who are totally oblivious to the concept of ORMs will probably be asking "What is Entity Framework? What are the benefits of using it and is it an alternative to ADO.NET?"

Well, to answer the first question about what is Entity Framework, Entity Framework is an Object Relational Mapper (ORM). It basically generates business objects and entities according to the database tables and provides the mechanism for:

1. Performing basic CRUD (Create, Read, Update, Delete) operations.
2. Easily managing "1 to 1", "1 to many", and "many to many" relationships.
3. Ability to have inheritance relationships between entities.

and to answer the second question, the benefits are:

1. We can have all data access logic written in higher level languages.
2. The conceptual model can be represented in a better way by using relationships among entities.
3. The underlying data store can be replaced without much overhead since all data access logic is present at a higher level.

and finally, the last question that whether it is an alternative to ADO.NET, the answer would be "yes and no". Yes because the developer will not be writing ADO.NET methods and classes for performing data operations and no because this model is actually written on top of ADO.NET, meaning under this framework, we are still using ADO.NET. So let us look at the architecture of Entity Framework (diagram taken from MSDN):

Using the code

Let's try to understand the ease of use that Entity Framework provides by performing simple CRUD operations. Once we look at the code and how effortlessly and efficiently we can do these operations, the benefits of Entity Framework will become quite obvious.

Creating the database

Let's have a simple database with one table. Let's create a simple table for Contacts and we will perform CRUD operations on this table.

Adding the Entity Model to the Website

Once we have the database ready, we can add the entity model to our website. We can do this by adding anADO.NET Entity Data Model to the website.

Once we select to add this data model to our website, we will have to select the approach we want to take for our Model's contents.

What this selection means is that we can either choose to generate the entity model from an existing database schema or we can design the entity model here and then later hook it up to the database. Since we already have the database ready, we will use the first option. Once the Model is generated, the Entity for each table is generated. The generated entity for our contact table is:

Also, the classes for performing database operations are also created. We just need to know how to use these classes to perform database operations.

Insert operation

Let us create a simple page to perform an insert operation.