How do I find my SID (session id) from SQL*Plus

The Oracle (tm) Users' Co-Operative FAQ

How do I find my SID (session id) from SQL*Plus/PLSQL.

There are 2 methods to determine my own SID (session id) either from SQL*Plus or PL/SQL. The first method may be used with Oracle 7.x and up, the second one only with Oracle 8i and up

Method 1 (for Oracle 7.x and up)

    SELECT sid FROM V$SESSION
         WHERE audsid = userenv('sessionid');
         SID
         ---
           9

Method 2 (for Oracle 8i and up - uses new function SYS_CONTEXT)

    SELECT sid FROM V$SESSION
         WHERE audsid = SYS_CONTEXT('userenv','sessionid');
         SID
         ---
           9.

Further reading: