System.Data.SqlClient.SqlException: Login failed for user 'IIS APPPOOL\DefaultAppPool' in IIS7

Introduction:

In this article I will explain how to solve  System.Data.SqlClient.SqlException: Login failed for user 'IIS APPPOOL\DefaultAppPool' problem in IIS7. 

Description: 

Recently I started working with IIS7 at that time I face some of strange problems to rectify those errors I did some modifications in IIS. After seen those errors I decided to write this post to help people who are need with this error.  I did one sample application and  deploy application in IIS. I started running my deployed application at that time I get error like this 

System.Data.SqlClient.SqlException: Login failed for user 'IIS APPPOOL\DefaultAppPool'

To solve this problem I made modifications in IIS configuration to make those changes just follow below steps to solve this problem.

Start ---> Open  Run and type  inetmgr and click OK now our  IIS will open

In IIS select  Application Pools ---> In that select  DefaultAppPool ---> Right Click on  DefaultAppPool---> Select  Advanced Settings

After open  Advanced Settings one window will open in that select  Identity and change path selection for  Identity

Now change the Identity path selection from  ApplicationPoolIdentity  to  LocalSystem

Select Built-in account to LocalSystem click OK now your problem will solve and it will work for you.