From: peter on

I am using firebird 2.0 database for my application. It runs at our client
site very well. But one day it did not work. Finally we found the client
installed some other application, that used lower version of firebird.

Now we are planning rewrite our application in .net and use sql server
express as database. Since much more applications use sql server than
firebird, will the firebird problem happens in sql server as well? I mean if
I use sql server 2008 express, if my client installs different versions of
sql server or sql server express before or after installing my application,
will this causes a trouble?

Many thanks

From: Eric Isaacs on
You can install different versions of SQL Server on the same server as
different instances when it comes to standard SQL Server. SQL Server
Express is limited to 1 GB of memory and 4 GB of storage. I'm not
sure how that is affected if you install SQL Server Express 2005 and
SQL Server Express 2008 on the same box, or if that is possible.

You can install standard editions of SQL Server 2000, 2005, and 2008
on the same machine and use them all independently as different
instances. You can also run SQL Server 2000 databases on SQL Server
2005 and 2008 running in SQL Server 2000 "compatibility mode" whereby
features from SQL Server 2000 are maintained in 2005 and 2008. (You
cannot however restore a SQL Server 2000 database that was backed up
from a 2005 or 2008 database and run in 2000 compatibility mode back
to SQL Server 2000 later.) So if the user "upgrades" to a new version
of SQL Server, that shouldn't prevent their old version of SQL Server
from still working with the same compatibility, nor would it prevent
existing functionality from breaking. If a user downgrades, which
doesn't really make sense, it would not be easy to restore the
database on that older version, if it had ever been run in the newer
version. You could script the database and migrate the data to the
older database, but depending on how complicated the data structure
is, that might be difficult and expensive. If a user installed an
older version of SQL Server, the solution in my mind would be to also
install the newer version again.

-Eric Isaacs