Issue connecting Oracle 11g to SQL Server 2012 — ORA-12523: TNS:listener could not find instance appropriate for the client connection

Question

I have Oracle 11g and SQL Server 2012 installed on the same virtual machine. OS is Windows Server 2012. I want to access SQL Server 2012 from Oracle. I created the machine a few days back to test the connection process before applying it on server.

I had come through several issues but now I am stuck with this one.

ORA-12523: TNS:listener could not find instance appropriate for the client connection

I have already created ODBC Connection by the name of sqldb.

kshaz is my machine name.

Following are my configuration details.

listener.ora file

# listener.ora Network Configuration File: C:\app\Administrator\product\11.2.0\dbhome_1\NETWORK\ADMIN\listener.ora
# Generated by Oracle configuration tools.

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = CLRExtProc)
      (ORACLE_HOME = C:\app\Administrator\product\11.2.0\dbhome_1)
      (PROGRAM = extproc)
      (ENVS = "EXTPROC_DLLS=ONLY:C:\app\Administrator\product\11.2.0\dbhome_1\bin\oraclr11.dll")
    )
    (SID_DESC =
      (SID_NAME = sqldb)
      (ORACLE_HOME = C:\app\Administrator\product\11.2.0\dbhome_1)
      (PROGRAM = hsodbc)
    )
  )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = kshaz)(PORT = 1521))
    )
  )

ADR_BASE_LISTENER = C:\app\Administrator

DIRECT_HANDOFF_TTC_LISTENER = OFF

tnsnames.ora file

LISTENER_ORCL =
  (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))


ORACLR_CONNECTION_DATA =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
    )
    (CONNECT_DATA =
      (SID = CLRExtProc)
      (PRESENTATION = RO)
    )
  )

ORCL =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = orcl)
    )
  )
SQLDB =
 (DESCRIPTION =
   (ADDRESS_LIST =
     (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))
   )
 (CONNECT_DATA =
   (SERVICE_NAME = sqldb)
 )
)

sqlnet.ora file

SQLNET.AUTHENTICATION_SERVICES= (NTS)

NAMES.DIRECTORY_PATH= (TNSNAMES, EZCONNECT)

initsqldb.ora file

HS_FDS_CONNECT_INFO = sqldb
HS_FDS_TRACE_LEVEL = off

I am running the following query.

select * from emptest@sqld

emptest is the table created at SQL Server 2012 and SQLD is the public database link.

Where have I gone wrong with the configuration? Or if there is any step that I have missed?

Thank you.