Set path to login to database and export

In NIX machine,

$export ORACLE_SID=<ORACLE_SERVICE_NAME>

$export ORACLE_HOME=<Path_to_ORACLE_SERVICE_NAME_in_ORATAB>

Navigate to the bin folder of the db_home

./sqlplus / as sysdba


 In Windows Machine

Check in services.msc

C:\set ORACLE_SID=<Oracle_service_name>

C:\set PATH=<Path to the bin file of the ORACLE_service_name>

C:\set ORACLE_HOME=<Path to the db_1 location of the database>

Then you can get into SQLPLUS prompt.

C:\sqlplus