Dot Net Thoughts

In the current project we are using Entity Framework for database operations. Entity Framework comes with Visual Studio SP1, which helps you to map tables / views / procedures as entities in C# / VB Code. You can find more details about EF from here : http://msdn.microsoft.com/en-us/library/bb399572.aspx. In this post I am explaining how to use Stored Procedures in Entity Framework.

1. Add the Stored Procedure to the Entity Model Designer using Update Model From Database Option.


Add Procedure

2. If you are added successfully, you can get the procedure in Model Browser.


Model Browser

3. Right click on the Procedure name and select Create Function Import.


Create Function Import

4. It will popups a Windows with Stored Procedure Name, Function Import Name and Return Type. If the procedure returns nothing, you can choose none. If the procedure is returns single value, like UserId, Number Of Rows etc, then you can choose scalar option, where you need to specify the return type. And if the procedure is returns Table or Number of Rows, you need to choose the last option Entities, which will allow to select entities created in the Model as the Output. Sometimes we need to create a View in the DB and need to import it in the Model, so that we can use the View as the return type entity. Select the appropriate return type and click Ok. You can use this in code. In this code I am using a View to return the selected users.

Add Function Import dialog

using (SampleEntities context = new SampleEntities())
{
/*
* Thanks to Barry Soetoro.
* I was not calling the GetAllUsers function.
List<Users> Users = null;
Users = (from user in context.Users
             select user).ToList();
this.dataGridView1.DataSource = Users;
*/
//Updated Version.
IEnumerable<UsersView> userview = context.GetAllUsers();
this.dataGridView1.DataSource = userview;
}

This will display list of Users in the DataGridView. Happy Coding

Normally for implementing Paging in Grid View, we enable the Paging property in GridView and will write code in the PageIndex Changed event. But the problem with this approach is it will fetch all the data from Database for Paging, will result wastage of network bandwidth and resources, also affect in the Page Performance. In SQL Server 2005 Microsoft introduced a new concepts called Row_Number() and Derived Table with the help these two we can move the Paging logic to Database instead of ASP.Net web forms. This concept also works with custom paging implementations for DataList or Repeater controls.

CREATE PROCEDURE usp_GetContacts
(@Page INT, @RecsPerPage INT)
AS
SELECT tblContacts.[Name], tblContacts.[IsParent] FROM
(SELECT ROW_NUMBER() OVER(ORDER BY [ID]) AS RowNumber,
[Name], [IsParent] FROM [TreeView].[dbo].[Contacts]) tblContacts
WHERE RowNumber > @RecsPerPage*(@Page) AND RowNumber <= @RecsPerPage*(@Page+1)

In this code we are creating a Column called “RowNumber”. And we are comparing the input parameters with the derived table tblContacts.

Thanks to Aneesh / Prasanth for their valueable suggestions and comments.