ERROR: ORA-12154: TNS:could not resolve the connect identifier specified

Question

Whenever I try to login or connect into SQL command line or SQL*Plus (11g Standard Edition Win64) I get an error
ORA-12154: TNS:could not resolve the connect identifier specified.
I have tried to solve this problem with google help but I can't.
so please help me out of this!

Solution

You are trying to connect to a database v. "v" is the connect identifier. However, your Oracle client does not know of v. This is what the error message is trying to tell you.

Try

c:>tnsping v

Hopefully this will give you something like this:

C:\Users\rwe>tnsping v

TNS Ping Utility for 64-bit Windows: Version 12.2.0.1.0 - Production on 21-MAR-2018 15:49:51

Copyright (c) 1997, 2016, Oracle.  All rights reserved.

Used parameter files:
C:\app\rwe\product\11.2.0\dbhome_1\network\admin\sqlnet.ora

TNS-03505: Failed to resolve name

What you can extract from this is the location:

C:\app\rwe\product\11.2.0\dbhome_1\network\admin\

This is where your tnsnames.ora file resides. Edit this file and add the correct information for your database v. Substitute servername for the machine your Oracle database is on.

V =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = tcp)(HOST = servername)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = V)
    )
  )