MSDE

[Jan Schenkel]

--- "tkuypers at pandora.be" <tkuypers at pandora.be> wrote:
> Hi Jan,
> 
> Is there a reason not to have direct support for MS
> SQL and MSDE?
> ODBC works ofcouse, but we are developing a scalable
> system and would like
> to be able to "upgrade" from MSDE to MS SQL or from
> MySQL to Oracle.
> The first one we can do through ODBC, but what
> happens when we want to
> switch from MSDE to Oracle or from MySQL to MS SQL?
> 
> Your advise is very welcome...
> 
> Warm regards,
> 
> Ton Kuypers
> 

Hi Tom,

As for direct support for more databases, you'll have
to ask the RunRev team. Judging by the fact that they
have added Valentina in version 1.1.1 and Postgresql
in version 2.0, this is a list that will grow over
time as the need arises.
At any rate, when you start migrating from one DBMS to
another under the hood, you'll encounter several small
differences between environmeents in terms of what SQL
is supported.

If you stick with a subset that is widely supported,
you'll be able to quickly hook up a different database
system without changing code ; otherwise you'll have
to change your queries.
MySQL for one doesn't support SELECT-within-SELECT
statements, and it has a few additional clauses you
won't find in Oracle (like the LIMIT clause in SELECT
statements) or that have a different name there.

And even then, you'll notice that some databases may
not support calls to revdb_movefirst, revdb_movelast ;
or have no support for transactions, so you can't use
revdb_commit and revdb_rollback.
So the best tactic is to scout the databases and which
instructions they support, and remain within their
common boundaries as often as you can, and add
workarounds for the differences you can't avoid.

Hope this helped,

Jan Schenkel.

=====
"As we grow older, we grow both wiser and more foolish at the same time."  (La Rochefoucauld)

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