How to get Oracle system change number (SCN) ?

The SYSTEM CHANGE NUMBER = A stamp that defines a committed version of a database at a point in time. Oracle assigns every committed transaction a unique SCN.

USER_A@MYDB 01022015 09:24:45> SELECT CURRENT_SCN FROM V$DATABASE;

CURRENT_SCN

-----------

    2544927

USER_A@MYDB 01022015 09:24:46> SELECT DBMS_FLASHBACK.GET_SYSTEM_CHANGE_NUMBER FROM DUAL;

GET_SYSTEM_CHANGE_NUMBER

------------------------

                 2544927

The User_A should have the privileges execute on DBMS_FLASHBACK and SELECT on V_$DATABASE