The LAST_DAY function retrieves the last day of the month in the specified date.
v_dt:= LAST_DAY (date);
SQL> SQL> declare 2 v_dt DATE; 3 v_form_tx VARCHAR2(25):= 4 'DD-MON-YYYY HH24:MI:SS'; 5 begin 6 v_dt:=last_day(sysdate); 7 DBMS_OUTPUT.put_line(to_char(v_dt,v_form_tx)); 8 end; 9 / 30-JUN-2007 20:32:45 PL/SQL procedure successfully completed. SQL>