Getting Oracle version number

What SQL statement would I use to get the version of Oracle I am using? For example, I would like to know what patch I currently have installed. I know I have version 8.1.7.? installed (where ? is the patch number), but don't know which patch version. Is there a view that I can query to get this information? If so, which one?

Thanks in advance,
shava

select * from v$version

Apart from v$version, one can use
"select * from product_component_version" also...

product_component_version Structure is -
product varchar2(64),
version varchar2(64),
status varchar2(64)