How can I confirm a database is Oracle & what version it is using SQL?

Two methods:

select * from v$version;

will give you:

Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production
PL/SQL Release 11.1.0.6.0 - Production
CORE 11.1.0.6.0 Production
TNS for Solaris: Version 11.1.0.6.0 - Production
NLSRTL Version 11.1.0.6.0 - Production

OR Identifying Your Oracle Database Software Release:

select * from product_component_version;

will give you:

PRODUCT VERSION STATUS
NLSRTL  11.1.0.6.0  Production
Oracle Database 11g Enterprise Edition  11.1.0.6.0  64bit Production
PL/SQL  11.1.0.6.0  Production
TNS for Solaris:    11.1.0.6.0  Production

Run this SQL:

select * from v$version;

And you'll get a result like:

BANNER
----------------------------------------------------------------
Oracle Database 10g Release 10.2.0.3.0 - 64bit Production
PL/SQL Release 10.2.0.3.0 - Production
CORE    10.2.0.3.0      Production
TNS for Solaris: Version 10.2.0.3.0 - Production
NLSRTL Version 10.2.0.3.0 - Production

SQL> SELECT version FROM v$instance;
VERSION
-----------------
11.2.0.3.0