Database link to the same database

I'm trying to create a database link to the same database.
It doesn't seem to be working ...
basically, the target system will have 2 separate database instances.
I need to emulate this in a single instance database (actually, I don't want to try running 2 oracle instances on my laptop...).
so I want to do select * from fred@MYOTHERDB
when I try and create the alias it succeeds, but then selects don't work.
Lets say my current logon / schema is JOHN (in ORCL) and the other SCHEMA (in ORCL) is JIM
I tried
create public database link MYOTHERDB connect to JIM identified by "Password";
creation worked, couldn't access it.
Thanks in advance
Iain

The machine with the database has tnsnames.ora as
# tnsnames.ora Network Configuration File: D:\oracle\product\10.1.0\Db_1\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.
INVMAN =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = xplaptop)(PORT = 1521))
(CONNECT_DATA =
(SERVICE_NAME = ORCL)
ORCL =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = xplaptop.mshome.net)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = orcl)
EXTPROC_CONNECTION_DATA =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC))
(CONNECT_DATA =
(SID = PLSExtProc)
(PRESENTATION = RO)
and the local (TOAD) machine has
# TNSNAMES.ORA Network Configuration File: S:\Oracle\product\NETWORK\ADMIN\tnsnames.ora
# Generated by Oracle configuration tools.
INVMAN =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = idc-server)(PORT = 1521))
(CONNECT_DATA =
(SID = INVMAN)
INVMANLAP =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = xplaptop)(PORT = 1521))
(CONNECT_DATA =
(SID = ORCL)
ORCL =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = idc-server)(PORT = 1521))
(CONNECT_DATA =
(SERVICE_NAME = ORCL)
Now I've tried this both from TOAD and from iSQL on the machine with the database.
It's INVMANLAP which I'm using from the TOAD machine, of course!
I appreciate your help. It has been the only bright spark in a DREADFUL day (among other things the IDC-SERVER mentioned above has a trashed system disk which has taken out email and my main oracle server). And I have to install this system tomorrow!
Iain

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Creating a database link to another schema in the same database

Hello,
I'm trying to create a database link to another schema in the same database. It was created without errors, but when I try to use it I receive "ORA-12154: TNS:could not resolve the connect identifier specified" message...
I'm trying to do it because on my production enviroment the databases are separated, so there I can use database links without problem, but in my development environment it's all in one database separated by schemas...
So I'm trying to simulate the same system to not need to rewrite the query every time I move from development to production environment.
Any ideas?
Thanks

Hi,
Yes, you can create a database link to your own database. I've done it before for exactly the same reason you want to.
(By the way, I think it's a good reason. What are the alternatives?
Having different versions of code for Development and Production? Absolutely not! Terrible idea!
Using synonyms or substitution variables that are set differently in the different databases? That might be more efficient than a database link, but efficiency probably isn't such a big issue in Development.
[Conditional compilation|http://download.oracle.com/docs/cd/B28359_01/appdev.111/b28370/fundamentals.htm#sthref250]? This might be good; it has all the efficienty of the above options, with more clarity.)
Assuming you do want to stick with a database link, not all errors are caught when you create the link.
Is the Development database in the tnsnames.ora file of the Development server? Do you have other database links, either in the Development server or pointing to it, that work? What is different about the ones that work, and the one that doesn't?
Edited by: Frank Kulash on Oct 14, 2009 1:58 PM
The more I think about this, the more I agree with the earlier respondent: synonymns are a good solution for this.
To that suggestion you replied:
On this way I might use "select * from SCHEMA.table" instead of "select * from table@SCHEMA"... I looking for an option to use the second way...Actually, the suggestion was that you say:
select *
from SCHEMA_table_ptr;where schema_table_ptr is a synonym.
In Development, that synonym is defined as schema.table.
In Production, that synonym is defined as table@SCHEMA
Why are you "looking for an option to use the second way"?
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Hi,
I need to establish a db link between two databases that are named the same way on two different servers.
server 1 has a database dev1 and server2 has a database dev1. The tnsnames on server2:
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adomi wrote:
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