How to find out sid of a query running?

How to find out session id of a sql that is running?

SELECT s.sid FROM v$session s, v$sqlarea a,v$process p WHERE s.SQL_HASH_VALUE = a.HASH_VALUE AND s.SQL_ADDRESS = a.ADDRESS AND s.PADDR = p.ADDR and a.sql_text like '%ALTER INDEX%';

Note: Where sql_text is some unique part of the sql running