Example 3-12 Implicit Conversion

DECLARE
   start_time   CHAR(5);
   finish_time  CHAR(5);
   elapsed_time NUMBER(5);
BEGIN
   /* Get system time as seconds past midnight. */
   SELECT TO_CHAR(SYSDATE,'SSSSS') INTO start_time FROM sys.dual;
   -- processing done here...
   /* Get system time again. */
   SELECT TO_CHAR(SYSDATE,'SSSSS') INTO finish_time FROM sys.dual;
   /* Compute elapsed time in seconds. */
   elapsed_time := finish_time - start_time;
   DBMS_OUTPUT.PUT_LINE( 'Elapsed time: ' || TO_CHAR(elapsed_time) );
END;
/