Make your queries Self Aware...

In past Oracle versions you may have used USERENV() to access some of this information. The information is now available in the 'USERENV' namespace of the sys_context function.

http://www.techonthenet.com/oracle/functions/sys_context.php

Here is a useful example. When monitoring the current in-flight SQL it is nice to exclude the current query from the results:

-- In Flight SQL
SELECT nvl(ses.username,'ORACLE PROC')||' ('||ses.sid||')' UNAM,
machine,
REPLACE(SQL.SQL_TEXT,CHR(10),'') STMT,
ltrim(to_char(floor(SES.LAST_CALL_ET/3600), '09')) || ':'
|| ltrim(to_char(floor(mod(SES.LAST_CALL_ET, 3600)/60), '09')) || ':'
|| ltrim(to_char(mod(SES.LAST_CALL_ET, 60), '09')) RUNT,
'ALTER SYSTEM KILL SESSION ''' || SID || ',' || SERIAL# || ''';' as killstmt
FROM V$SESSION SES,
V$SQLtext_with_newlines SQL
where SES.STATUS = 'ACTIVE'
and SES.USERNAME is not null
and SES.SQL_ADDRESS = SQL.ADDRESS
and SES.SQL_HASH_VALUE = SQL.HASH_VALUE
and Ses.AUDSID <> sys_context( 'USERENV', 'SESSIONID')
order by runt desc, 1,sql.piece;

For a complete list of other parameters and more extensive detail on how the values returned might be used, please review the Oracle 9i SQL Reference.

-- Dave