Oracle Query to Get Database Information like Version, db size, avilable size, file location

select round(sum(used.bytes) / 1024 / 1024 / 1024 ) || ' GB' "Database Size"

, round(sum(used.bytes) / 1024 / 1024 / 1024 ) - 

round(free.p / 1024 / 1024 / 1024) || ' GB' "Used space"

, round(free.p / 1024 / 1024 / 1024) || ' GB' "Free space"

from    (select bytes

from v$datafile

union all

select bytes

from v$tempfile

union all

select bytes

from v$log) used

, (select sum(bytes) as p

from dba_free_space) free

group by free.p;

SELECT version FROM V$INSTANCE; --11.2.0.1.0

SELECT * from PRODUCT_COMPONENT_VERSION; -- Get detailed version

SELECT * from dba_data_files ;  --Get Physical file

SELECT * from V$SESSION Where Status='KILLED'; -- Get Oracle connected sessio list

SELECT * from V$SQL ;-- Get All Executed Query details