Okay I agree that if you use only ExecuteSQL in the dal+ and you use "standard" SQL you have a hope of database independence on those calls. 

Is it possible to create a single script to create the tables and indexes for a module that you can guarantee with work in SQL server, Oracle, Access and MySQL?  I do not know if table creation is part of the entity spaces stuff.  It wasn't obvious form the information I have read.  I will need to spend more time on that.  I would guess that it is not a slam dunk to easily define tables in oracle, MySQL, Access and SQL server without compromises.  There are differences between the databases here is an article talking about datatype interoperability.  There are issues.

Even if it is possible with entity spaces or the table definition and index creation is common among all the databases and it is simple.  You have to test on all of them.  That would quadruple the database access testing on a module.  I would guess that testing is rarely sufficient now.  It will certainly get worse.  Developers won't have SQL Server, Oracle, MySQL and Access all running to test.  It just seems impractical.  True swappable database providers is a figment of our imagination as it is right now unless every part is taken care of in the dataprovider and that will be too limiting. 

It's like writing a program in C.  You should be able to write source and compile that same code on Linux, UNIX and windows and have the program work on all systems.  But it only works for very simple things. 

mj

A lot of work by a lot of people for years has been spent on this issue (for example: DAL Project/FireBirdDotNuke Project ) . We believe that we currently deliver the best solution with the DAL/DAL+

mhj96813 wrote It's like writing a program in C.  You should be able to write source and compile that same code on Linux, UNIX and windows and have the program work on all systems.  But it only works for very simple things.

I think the issue to keep in mind is that with databases you are crossing a "boundary" from your computer program into a system (the database) that is completely separate and usually unique. With .Net vs. Linux they are targeted to the same hardware. With SQL vs. MySQL you have completely different systems.

Trying to create a generic way to talk to systems so completely different is almost impossible. All we really have is standard SQL (and that is not perfect. For example table creation scripts and index optimization is just plain different in each database). Therefore the ExecuteSQL is as close as I believe you will ever come.

We now provide that in the DAL+. Give it a try. I belive it will come as close as anything to meeting your needs.