How to query cross-database?

Question

I need do a query over a table on the connected database server and another table on another database server. How I can I do it in a easy way?
Can you write you query as easily as:
Select a, b from table 1, table2@server2 where a.c1=b.c1
The other question is:
If you close the database connection but do nothing with statement, will the statement get closed implicitly?
Thanks in advance,
YM

Answer 1

I need do a query over a table on the connected
database server and another table on another database
server. How I can I do it in a easy way?
Can you write you query as easily as:
Select a, b from table 1, table2@server2 where
a.c1=b.c1Some DBMSses have features that allow you to access tables on other databases (maybe on other servers even). The behaviour and the code syntax should be found in the docs.
No standart SQL.
Alternatively: your Java program can do several connections to several databases. So - not by a simple joined select, but by some more logic - you can do your cross-db query.
The other question is:
If you close the database connection but do nothing
with statement, will the statement get closed
implicitly?I think, yes. But you never know what some specific driver for some specific DBMS will do.
It's more clean to close the statement explicitely.
Either use the same statement(s) always, then create it/them directly after connecting and close it/them directly before the connection,
or create a new statement for each task and close it afterwards.