Entity Framework 4.0 - Class library - Part 1

In this blog post we are going to explore how to create the data access layer as a
class library using Entity Framework 4.0. By defining the data access layer as
class library, you can reuse it across many applications just by adding a
reference to the class library. In my next blog post, we'll explore how to consume
the library in an application



Entity Framework 4.0 enables the developer to
concentrate on the business logic and business objects without bothering how it
has been manipulated at the database level. You can find a very good tutorial on
Entity Framework
here to get started.



This blog post uses a sample database named "HRD" which has two tables, Employee and Department.

Step 1: Create a Class Library

Create a new class library project with the name "HRD.DataAccess" and click "Ok"



After creating a new project delete the "Class1.cs" which is created by default.

Step 2: Create the Entity class using the entity framework

Right click on the project name "HRD.DataAccess" and select "Add -> New item".
Select "Data" under installed templates and then select "ADO.NET Data Entity Model".
Type the name as "HrdModel.edmx" and click "Add"




In the Entity Data Model Wizard select "Generate from database" and click "Next"




In the next step select the database name "PCName\sqlexpress.HRD.dbo" and select "Next"




In the next step select the tables names "Department" & "Employee" and click "Finish"



Now we have created the entity model which represent the Object/Relation mapping

Step 3: Building the class library

1. Select "Build->Configuration Manager"
2. Change the Configuration of the Project "HRD.DataAccess" to "Release". By default it is "Debug"
3. Click "Close"
4. Select "Build->Build HRD.DataAccess"

Thats it!!. Now we have the DataAccess Library ready!! We can reuse it across different .Net Applications

Summary

In this blog we have explored the way of creating the DataAccess class library using entity framework.
in my next blog, we'd explore on how to consume the data access library in an application.

SQL CE

Deploying a database in the production server is always a tidy task for the developer.
Installation issues, security issues, migration from development to production
the list goes… This scenario holds good only for network based database. To
avoid this overhead (Headache too!!) some developers may opt for MS Access. This
Access based solution will not work for you if you are going to develop large
database centric application.



You may ask, I am going to leverage only minimal use of database in my
application, so what’s wrong in using access? Good Catch!! You can use access,
so that you can carry your database wherever you are deploying the application.
Hold on, by doing so you are losing a magic. Yes magic! The name of the magic is
Entity Framework. Using Entity Framework you can speak to your database with few
lines of coding and create application in minutes (even in seconds). Sounds
interesting! Do google "Entity Framework"!!.



Fine,Thinking about the solution ?? The answer is SQL CE.


SQL CE is a free, embedded, database engine that enables easy database storage.It does not require you to install a database server in order to use it. You can carry the database in the same way as you did for access by simply copying the SQL CE binaries to the \bin directory of your application.



Advantages of SQL CE

• No installation/security issues.
• Works with existing Data APIs - ADO.NET,Entity Framework, etc.,
• Suitable for light production scenarios
• No License restrictions. Absolutely Free :-)
• Can be migrated to SQL Server, SQL Express or SQL Azure easily

You can download SQL CE from here.