To find out which queries are running in database, login as SYS and issue the following query:
SELECTa.USERNAME, a.STATUS, b.sql_text
FROM V$SESSION a INNER JOIN V$SQLAREA b
ON a.SQL_ADDRESS= b.ADDRESS;
V$SESSION view lists session information for each current session.
To see field-wise description for V$SESSION follow the link below:
V$SQLAREA lists statistics on shared SQL area and contains one row per SQL string. It provides statistics on SQL statements that are in memory, parsed, and ready for execution.
To see field-wise description for V$SQLAREA follow the link below: