Where queries should be placed in ASP.NET MVC

Question

I am using ASP.NET MVC, building an ERP with Framework 4.0 and SQL Server 2008.
My question is where should query be placed? I saw multiple methods while surfing. Few of them are as follows:

• In Models
• In Separate Files, that are in DAL Folder
• In Separate DAL Project

I am still confused about using queries in Models after research.

Further Info:
I am using simple query method, not Linq and Entity Framework.
I have a plan to also convert this project to Desktop Application in future.

Another Question is that How business Logic works in ASP.NET MVC if I use it?

Detail About Project
It is a Website + Online Information System of a Company with around 40-50 pages of both.
User can enter in Info System by Signing in from website.

Before Voting to Close Leave a comment so that I can learn something.

Answer 1

Your question is about infrastructure of a project that depends on lots of factors.

Considering the information you have provided in your question:

I have a plan to also convert this project in Desktop Application in future.

for the sake of usability, you should have your Data Access Layer in a separate project.

If you are interested in obtaining more information about the infrastructure of a project, I recommend to you: Microsoft Spain - Domain Oriented N-Layered .NET 4.0 Sample App that is well documented and gives you much information that you need to produce an enterprise level application.