db-derby-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Rick Hillegas <Richard.Hille...@Sun.COM>
Subject Re: Queries in two differents databases ( connections)
Date Tue, 27 Nov 2007 17:39:45 GMT
Hi Cíntia,

Derby does not have any builtin support for distributed joins--that is 
for running a query which mentions tables in two different databases. 
However, you may be able to accomplish what you need to do by using 
table functions, a feature that is implemented in the development trunk 
and which we expect to expose in Derby 10.4 next year. Table functions 
are described in the "Programming Derby-style table functions" section 
of the Derby Developer's Guide: 
http://db.apache.org/derby/docs/dev/devguide/ Examples of how to use 
table functions (including how to write a table function which wraps a 
table in another database) can be found in the demo code in the 
development trunk at java/demo/vtis--just start with the README file there.

Using table functions, you could fake a distributed join with syntax 
like this:

SELECT *
FROM localTable, TABLE( foreignTableFunction() ) foreignTable
WHERE localTable.keyCol = foreignTable.keyCol

Hope this helps,
-Rick

Cíntia wrote:
> Hi,
>
> I need do a query in two tables of differents databases, this is
> possible? I can do this in java or just using SQL?
>
> Thanks,
>
> Cíntia Nogueira
>
>   


Mime
View raw message