Connection Between Two Databases

Question

Hi,
I have two databases called DBS1 and DBS2. Both are in one system. I need link between these two databases. I want a query as follows.
select * from cust@DBS2; # from DBS1
select * from temp_cust@DBS1; # from DBS2
Is possible link between DBS1 and DBS2.
Can any one tell me how to link these two databases each other.
Best Regards,
Nilopher.
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Answer 1

Nilopher,
You can connect to two different Oracle databases by creating a database link. When you say that both databases are in one system I assume you mean two databases on the same server. To create a database link you can do the following:
While logged onto DBS1:
create database link dbs2
connect to username identified by password
using 'dbs2.world'
Username and password are the user and password you want to connect as in dbs2.
If you want everyone to be able to access the database link you can say create public database link... otherwise only the user that created the database link can use it.
This should work assuming the database server tnsnames.ora file looks like this:
dbs2.world =
(DESCRIPTION =
(ADDRESS = (PROTOCOL= TCP)(Host= hostname)(Port= 1521))
(CONNECT_DATA = (SERVICE_NAME = dbs2))
If your databases are on two different servers you'd have to look at each one's tnsnames.ora file and make sure each one had an entry for the other's database.
I believe the database link name must be the same as the SERVICE_NAME if the parameter GLOBAL_NAMES=TRUE, if it's FALSE you can name it something else. By default this parameter is set to TRUE so I called the database link in the example dbs2.
You can then access data from dbs2 while logged into dbs1 exactly how you said:
select * from cust@DBS2;
You can then repeat the process to do the same thing on dbs2 to connect to dbs1.
Hope this helps.