Subject Re: [firebird-support] Re: Can SQL be used in two DBs
Author Maurice Ling

This may be OT for the original question. I have a feeling that recently
there is an increase in support queries for cross-database queries (i.e.
this type of emails). It brings me to wonder if there is an increasing
need for work in this area. At the same time, I do not know if SQL99 or
SQL2003 have support for this. However, I can see that with more
federated databases, the need for cross-database operations may increase.

Just my opinions.


Adam wrote:

> --- In, Aage Johansen <aagjohan@o...>
> wrote:
> > Carlos Ortiz Quiros wrote:
> > > I wonder if I could use two databases, one named
> > > db1.fdb and the other db2.fdb. On db1 I have table1
> > > with fields field1 as int, field2 as varchar(200) and
> > > the same goes for db2.
> > >
> > > Question is:
> > > Could I write a JOIN SQL to see which records are in
> > > one table that are not in the other
> > > Is it possible?
> >
> >
> > No.
> >
> > --
> > Aage J.
> Just to repeat what Aage said, No.
> You can however span the same transaction over multiple databases, so
> your client program could request the data from both databases and
> internally do the join.
> It would not be particularily efficient if the tables were large. If
> you are trying to do some sort of replication, then there are other
> ways of achieving this.
> Adam

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