Rename the Database with and without NID

Check the below parameters and values.

show parameter db_name-->spfile
or
select name from v$database;

alter database backup controlfile to trace as '/oradata/dbname/c1text.sql';
shut immediate
mv /oradata/dbname/control01.ctl /oradata/dbname/control01.ctl_old

mv /oradata/dbname/control02.ctl /oradata/dbname/control02.ctl_old

startup nomount
alter system set db_name='test' scope=spfile;

select name,value from v$spparameter where name='db_name';

cp -p /oradata/dbname/c1text.sql /oradata/dbname/c1text.sql_bkp

vi /oradata/dbname/c1text.sql

There will be 2 set of controlfile creation script in SQL file.
Delete colplete 1st set and change below  first line in backup controlfile sql.

reuse ==>set
olddb ==>newdb
noresetlogs==>resetlogs


SQL>@ /oradata/dbname/c1text.sql
.
SQL>alter database open RESETLOGS;

select file#,name from v$datafile;
select file#,name from v$tempfile;

you will get renamed database  while query to v$database.

Rename DB With NID 

select tablespace_name,status from dba_tablespaces;
*********************************************
shut immediate
startup mount
select name,open_mode,log_mode,dbid from v$database;
##nid target=/ DBNAME=NEWTEST
nid target=/ DBNAME=NEWTEST SETNAME=Y
startup nomount
alter system set db_name='NEWTEST' scope=spfile;
shut immediate
startup
*********************************************