Let's say I have an Oracle database. I have a username = x, password = y, database = z, port = a, SID = b, and Hostname = c.

So, how do I connect correctly? I used many options like:



But they usually give me the following errors:

ORA-12560: TNS:protocol adapter error
ORA-12514: TNS:listener does not currently know of service

  • 3
    Assuming you have the right host/port, it sounds to me like the instance isn't running or not registered with the listener. May 13, 2014 at 11:44
  • 2
    using ezconnect: sqlplus x/y@c:a/b May 14, 2014 at 15:45
  • 1
    for the record, your second example (at least) works for me if I surround it with quotes. like x@"(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=c)(PORT=a))(CONNECT_DATA=(SID=b)))"
    – rogerdpack
    Feb 18, 2015 at 22:04

7 Answers 7


Did you try:

sqlplus username/password@host:port/service
sqlplus x/y@c:a/b

Modern versions of sqlplus (11 and higher) understand this syntax and you don't need a tnsnames.ora file.

  • 1
    Default Port Number: 1521
    – Ivan Chau
    Aug 31, 2016 at 7:28
  • 4
    I have SID instead of service so using ":" instead of "/" worked for me sqlplus username/password@host:port:sid Mar 27, 2017 at 9:04
  • 1
    sqlplus that comes withv11. doesn't support host:port syntax. Seems already supports...
    – gavenkoa
    Jan 20, 2019 at 18:59
  • Shame on me for being at the mercy of tnsnames.ora. Zero deps forever Feb 22 at 21:36

The most simple is to use tnsnames.ora file to connect to the database. For that edit it and add a new entry: This file normally resides in the $ORACLE HOME\NETWORK\ADMIN directory.

myDb  =
     (ADDRESS = (PROTOCOL = TCP)(Host = c)(Port =a))

and then you could connect to the db:

sqlplus x/y@myDb


To original poster... in the first option you missed a closing parenthesis

Incorrect: (Your string)




SQL*Plus shows this syntax

Usage: CONN[ECT] [{logon|/|proxy} 
where <logon> ::= <username>[/<password>][@<connect_identifier>]
  <proxy> ::= <proxyuser>[<username>][/<password>][@<connect_identifier>]

If you use CMD window do

sqlplus /nolog 
connect sys/pwd@service as sysdba

also, I suggest not to include password into conn string. Enter it on the second prompt. This way it is not visible. And also, for Ora19 this is the connection syntax I was able to use successfully, without tnsnames

C:\WINDOWS\system32>sqlplus /nolog 
SQL> connect sys@'(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=myhostname)(PORT=1522))
Enter Password:

Your sqlplus line looks correct, verify the following:

  1. You can connect as sysdba on the database server itself.
  2. You can connect as the user you are trying to on the database server itself.
  3. You can ping the database server from the computer you are trying to connect from.
  4. You can tnsping the listener from the computer you are trying to connect from.

If all these check out you may want to create a fresh connection line to make sure you don't have a typo.


Maybe your database is not up. If the machine was restarted and the instance is not set to autostart (and it was not started manually), you may need to start the service yourself.

If you have access to the Services screen, you can do it from there; or, you can do it from the command line.

Go to Command prompt and enter the following commands:

set oracle_sid=ORCL

net start oracleserviceORCL

The first sets the Oracle SID; the second actually starts the service.


extract from sqlplus help :

can be in the form of Net Service Name or Easy Connect.

  @[<net_service_name> | [//]Host[:Port]/<service_name>]

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