How to get the size of an Oracle database

If you need to get the size of an Oracle database (excluding software, logs and things like that), you can do that this way:

SQL> select 'ONLINE_REDOLOG' as TYPE, sum(BYTES*MEMBERS)/1048576 as SIZE_MB from v$log union
select 'DATAFILES', sum(BYTES)/1048576 from v$datafile union
select 'TEMPFILES', sum(BYTES)/1048576 from v$tempfile union
select 'CONTROLFILES', sum(BLOCK_SIZE*FILE_SIZE_BLKS)/1048576 from v$controlfile union
select 'FLASH_RECOVERY_AREA', VALUE/1048576 from v$parameter where NAME='db_recovery_file_dest_size';

TYPE                   SIZE_MB
------------------- ----------
CONTROLFILES           14.1875
DATAFILES                 1230
FLASH_RECOVERY_AREA       3072
ONLINE_REDOLOG             300
TEMPFILES                   25