Re: The wisdom of the object mentors (Was: Searching OO Associations with RDBMS Persistence Models)

> Decoupling is good, if done at an appropriate level. However, given
> your preference for swapping out DBMSs "at a whim" you clearly have no
> choice but to use the lowest common denominator abilities of all DBMSs
> that might be chosen, which probably amounts to some very simple
> low-level DML and SELECT statements. Then you effectively build your
> own pseudo-DBMS on top of this with application code. What a waste of
> time and effort, not to mention the money you spent buying a DBMS of
> which you refuse to use 95% of the power!

This is simply not true. I have been converting a major enterprise application from Informix to also support Oracle and SQL Server. I think that we had to rewrite less than 5% of the SQL statements. In almost every case we were able to use the same query for all vendors without changing the semantics of the original query. In some severe cases we had to "wash" the SQL statement using simple find/replace functions, to fit different vendors. The conclusion was obvious: Continue to embedd (ANSI) SQL in the application, but make your own (JDBC/ODBC/ADO) driver on top of the vendor driver, to eliminate the remaining incompatibilites between vendors.

Fredrik Bertilsson
http://frebe.php0h.com Received on Wed May 31 2006 - 18:43:43 CEST