I have installed Oracle 11g r2 on Centos. On initial setup it installed database named ORCL for me.I setup listener.ora and tnsnames.ora for `ORCL` and on reboots all I had to do was run `lsnrctl start` command the instance by using following command `sqlplus /as sysdba` and `SQL>startup`.Now I needed another database I created another database using dbca as that was recommended by oracle(I think I should have used sql). New database named `hayer_test` with SID `hayertest`was installed in same directory as `ORCL` and it was up and running after install(before reboot).Now I rebooted the OS and when I did the steps I used to do only `ORCL` database came up.Not sure how to bring this second database up. Here the error I get when I try to connect now. SQL*Plus: Release 11.2.0.1.0 Production on Thu Jun 26 11:28:45 2014 Copyright (c) 1982, 2009, Oracle. All rights reserved. Enter user-name: system@hayer_test Enter password: ERROR: ORA-12514: TNS:listener does not currently know of service requested in connect descriptor My tnsnames.ora and listener.ora file contains this: listener.ora: LISTENER = (DESCRIPTION_LIST = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = hayer)(PORT = 1522)) ) ) ADR_BASE_LISTENER = /u01/app/oracle tnsname.ora: LISTENER_HAYERTEST = (ADDRESS = (PROTOCOL = TCP)(HOST = hayer)(PORT = 1522)) HAYER_TEST = (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = hayer)(PORT = 1522)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = hayer_test) (SID = hayertest) ) ) LISTENER_ORCL = (ADDRESS = (PROTOCOL = TCP)(HOST = hayer)(PORT = 1522)) ORCL = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = hayer)(PORT = 1522)) ) (CONNECT_DATA = (SERVICE_NAME = orcl) (SID = orcl) ) ) `lsnrctl status` command gives me following result : LSNRCTL for Linux: Version 11.2.0.1.0 - Production on 26-JUN-2014 11:23:23 Copyright (c) 1991, 2009, Oracle. All rights reserved. Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=hayer)(PORT=1522))) STATUS of the LISTENER ------------------------ Alias LISTENER Version TNSLSNR for Linux: Version 11.2.0.1.0 - Production Start Date 26-JUN-2014 10:22:53 Uptime 0 days 1 hr. 0 min. 30 sec Trace Level off Security ON: Local OS Authentication SNMP OFF Listener Parameter File /u01/app/oracle/product/11.2.0/db_1/network/admin/listener.ora Listener Log File /u01/app/oracle/diag/tnslsnr/hayer/listener/alert/log.xml Listening Endpoints Summary... (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=hayer)(PORT=1522))) Services Summary... Service "orcl" has 1 instance(s). Instance "orcl", status READY, has 1 handler(s) for this service... Service "orclXDB" has 1 instance(s). Instance "orcl", status READY, has 1 handler(s) for this service... I registered the database with listener when I installed database first time. Ran `SQL> show parameter local_list;` and got this result : NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ local_listener string (ADDRESS = (PROTOCOL=TCP)(HOST =hayer)(PORT=1522)) The command completed successfullyI am new to this and learning please help.Also if anyone can recommend most efficient way of creating databases in Oracle(dbca or sql query).