Extract the filename from a full file path unix select substr(file_name,(instr(file_name,'/',-1,1)+1),length(file_name)) FROM dba_data_files; windows select substr(file_name,(instr(file_name,'\',-1,1)+1),length(file_name)) FROM dba_data_files; Validates a long filename using Windows' rules: select file_name from table_of_files WHERE not REGEXP_LIKE(file_name,'^[^\\\./:\*\?\" \|]{1}[^\\/:\*\?\" \|]{0,254}$'); combinning these two SQLs: WITH files AS ( select substr(file_name,(instr(file_name,'/',-1,1)+1),length(file_name)) base_filename FROM dba_data_files) select base_filename from files WHERE REGEXP_LIKE(base_filename,'^[^\\\./:\*\?\" \|]{1}[^\\/:\*\?\" \|]{0,254}$');