Forms 6 not connecting with Database 10g

Question

I can not connect Oracle forms 6 with database 10g

Answer 1

795192 wrote:
I can connect to sql plus but i cannot connect my forms 6 with database 10g. getting the following error:
ORA-12154: TNS: could not resolve service name=================================
ORA-12154: TNS:could not resolve the connect identifier specified
This error means one thing, and one thing only. The client could not find the specified entry in the tnsnames.ora file being used.
As a follow-on to that statement, remember that when you use a dblink, the database in which the link is defined is acting as a client to the database that is the target of the link. So in this case, the tnsnames.ora file on the host of your source should have an entry for your target db, as defined in the db_link.
And for the umpteenth time ... this error has <b><i><u>NOTHING</u></i></b> to do with the status of a listener. The connection request never got far enough to reach a listener. If anyone tells you to check a listener in response to ora-12154, they are not paying attention, or do not understand how TNS works. This error is the equivalent of not being able to place a telephone call because you don't know the number of the party you want to reach. You wouldn't debug that situation by going to the other guy's house and testing his telephone, or by going to the phone company and testing the switchboard. And you don't debug a ORA-12154 by checking the listener. If I had a top ten list of "Incredibly Simple Concepts (tm)" that should be burned into the brain of everyone who claims to be an Oracle DBA, it would include "ORA-12154 Has Nothing To Do With The Listener".
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A couple of important points.
First, the listener is a server side only process. It's entire purpose in life is to receive requests for connections to databases and set up those connections. Once the connection is established, the listener is out of the picture. It creates the connection. It doesn't sustain the connection. One listener, with the default name of LISTENER, running from one oracle home, listening on a single port, will serve multiple database instances of multiple versions running from multiple homes. It is an unnecessary complexity to try to have multiple listeners or to name the listener as if it belongs to a particular database. That would be like the telephone company building a separate switchboard for each customer.
Second, the tnsnames.ora file is a client side issue. It's purpose is for address resolution - the tns equivalent of the 'hosts' file further down the network stack. The only reason it exists on a host machine is because that machine can also run client processes.
Assume you have the following in your tnsnames.ora:
larry =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = myhost)(PORT = 1521))
    (CONNECT_DATA =
      (SERVICE_NAME = curley)
  )Now, when you issue a connect, say like this:
$> sqlplus scott/tiger@larrytns will look in your tnsnames.ora for an entry called 'larry'. Next, tns sends a request to (PORT = 1521) on (HOST = myhost) using (PROTOCOL = TCP), asking for a connection to (SERVICE_NAME = curley).
Where is (HOST = myhost) on the network? When the request gets passed from tns to the next layer in the network stack, the name 'myhost' will get resolved to an IP address, either via a local 'hosts' file, via DNS, or possibly other less used mechanisms. You can also hard-code the ip address (HOST = 123.456.789.101) in the tnsnames.ora.
Next, the request arrives at port 1521 on myhost. Hopefully, there is a listener on myhost configured to listen on port 1521, and that listener knows about SERVICE_NAME = curley. If so, you'll be connected.
What can go wrong?
First, there may not be an entry for 'larry' in your tnsnames. In that case you get "ORA-12154: TNS:could not resolve the connect identifier specified" No need to go looking for a problem on the host, with the listener, etc. If you can't place a telephone call because you don't know the number (can't find your telephone directory (tnsnames.ora) or can't find the party you are looking for listed in it (no entry for larry)) you don't look for problems at the telephone switchboard.
Maybe the entry for larry was found, but myhost couldn't be resolved to an IP address (say there was no entry for myhost in the local hosts file). This will result in "ORA-12545: Connect failed because target host or object does not exist"
Maybe there was an entry for myserver in the local hosts file, but it specified a bad IP address. This will result in "ORA-12545: Connect failed because target host or object does not exist"
Maybe the IP was good, but there is no listener running: "ORA-12541: TNS:no listener"
Maybe the IP was good, there is a listener at myhost, but it is listening on a different port. "ORA-12560: TNS:protocol adapter error"
Maybe the IP was good, there is a listener at myhost, it is listening on the specified port, but doesn't know about SERVICE_NAME = curley. "ORA-12514: TNS:listener does not currently know of service requested in connect descriptor"
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