If your user account has autotrace configured by the DBA, you can use the "SET AUTOTRACE ON STATISTICS" command to turn on execution statistics reports on query statements. The tutorial exercise bellow shows you a good example:

SQL> CONNECT HR/retneclgg

SQL> SET AUTOTRACE ON STATISTICS

SQL> SELECT E.LAST_NAME, E.SALARY, J.JOB_TITLE

2 FROM EMPLOYEES E, JOBS J

3 WHERE E.JOB_ID=J.JOB_ID AND E.SALARY>12000;

LAST_NAME   SALARY JOB_TITLE

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

King    24000 President

Kochhar   17000 Administration Vice President

De Haan   17000 Administration Vice President

Russell   14000 Sales Manager

Partners   13500 Sales Manager

Hartstein   13000 Marketing Manager

6 rows selected.