>Hi Jim,
>What is different between Data Layer and Data Storage Layer?
>I'm not sure, I'm not understand you: what is Data Storage Layer ?
>
>Thanks for help,
>Vojislav C.

Data Access layer is the code that accesses the data throguh queries and inserts and updates. The data storage layer is where the data is stored and the where the data integrity rules are enforced. Examples of dtat storage layers might be SQL Server or Oracle with Stored procs and triggers controlling the data integrity. Or you could use VFP database with triggers as the data storage layer.

Separating the business logic from the data access allows you to implement business logic code that is independant as to where the data may be stored or how it will be accessed. So you could have a system designed something like this;

      Desktop Presentation                   Web Presentation
              |                                     |
              ---------------------------------------
                                 |
                           Business Logic
                                 |
                    |--------------------------------|
             ODBC Data Access                  VFP Data Access
                    |                                |
        |------------------------|                   |
        |                        |                   |   
        |                        |                   |
 SQL Server Data           Oracle Data            VFP Data