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This may be that your oracle server looks for the tnsnames.ora file in a different place than sqlPlus. The first thing I would do is a search on tnsnames.ora and if there are multiple files by that name, make sure they all contain the service name descriptor in question. Also I like to set up the TNS_ADMIN variable to point to the location where I keep my tnsnames.ora file. This way I know for sure where all the components are SUPPOSED to find it.
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This may be that your oracle server looks for the tnsnames.ora file in a different place than sqlPlus. The first thing I would do is a search on tnsnames.ora and if there are multiple files by that name, make sure they all contain the service name descriptor in question. Also I like to set up the TNS_ADMIN variable to point to the location where I keep my tnsnames.ora file. This way I know for sure where all the components are SUPPOSED to find it.

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drop database link aaa;<br />
<br />
create public &nbsp;database LINK aaa CONNECT TO scott IDENTIFIED BY tiger USING 'mydb' ;<br />
<br />
Error is:<br />
<br />
--select * from table1@mydb;<br />
<br />
<br />
Right is:<br />
<br />
select * from table1@aaa;<br />
<br />
OK?<br />
<br />
The string 'mydb' should in tnsnames.ora file.
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drop database link aaa;

create public  database LINK aaa CONNECT TO scott IDENTIFIED BY tiger USING 'mydb' ;

Error is:

--select * from table1@mydb;


Right is:

select * from table1@aaa;

OK?

The string 'mydb' should in tnsnames.ora file.

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<div class="content wysiwyg-content">
I created database link between 2 instances and the message says database link created..but I could not describe or select any tables from the remote database..<br />
<br />
here is my commands<br />
<br />
drop database link aaa;<br />
<br />
create public &nbsp;database LINK aaa CONNECT TO scott IDENTIFIED BY tiger USING 'mydb' ;<br />
<br />
select * from table1@mydb<br />
<br />
ORA -12154 TNS could not resolve service name .. but the same db is in tnsnames.ora and it works when &nbsp;I do sqlplus..<br />
sqlplus scott/tiger@mydb<br />
<br />
Can you guys figure out what is wrong here..<br />
<br />
Thanks<br />

</div>
</div>


I created database link between 2 instances and the message says database link created..but I could not describe or select any tables from the remote database..

here is my commands

drop database link aaa;

create public  database LINK aaa CONNECT TO scott IDENTIFIED BY tiger USING 'mydb' ;

select * from table1@mydb

ORA -12154 TNS could not resolve service name .. but the same db is in tnsnames.ora and it works when  I do sqlplus..
sqlplus scott/tiger@mydb

Can you guys figure out what is wrong here..

Thanks


Database link

Oracle is an object-relational database management system. It supports a large number of languages and application development frameworks. Its primary languages are SQL, PL/SQL and Java, but it also includes support for C and C++. Oracle also has its own enterprise modules and application server software.