ORA-01157: cannot identify/lock data file 201 SQL&gt;  select FILE_NAME,TABLESPACE_NAME from dba_temp_files;
                                   *



  ERROR at line 1: ORA-01157: cannot identify/lock data file 201 - see
  DBWR trace file ORA-01110: data file 201: '/oradata_nocg/temp01.dbf'


In the database I don't have '/oradata_nocg/temp01.dbf', I am not doing any operation related temp tablespace  Why it is not allowing run above select query. ?
Most likely this is in a database that was cloned from an other database and the tempfiles are not added. Oracle needs a functional temporary tablespace to be able to process joins and sorts. dba_temp_files is a view that does this.
Solution is to simply add a few tempfiles to the temporary tablespace.