Procedure credit_Intrest is

v_tot   number;

v_res   number;

v_tp    number;

v_start_date   date;

v_end_date     date;


Begin

 v_res  := v_tot/v_tp*(v_start_date -v_end_date);
end;

End credit_Intrest;

CREATE OR REPLACE
Procedure credit_Intrest 
is
  v_tot          number;
  v_res          number;
  v_tp           number;
  v_start_date   date;
  v_end_date     date;
Begin
  v_res  := v_tot/v_tp*(v_start_date -v_end_date);
EXCEPTION
  WHEN ZERO_DIVIDE THEN v_res := 0;
End credit_Intrest;
/

v_res := case when (v_start_date - v_end_date) = 0 then 0 else v_tot/v_tp*(v_start_date -v_end_date) end;

v_res := v_tot/v_tp*decode((v_start_date -v_end_date),0,<value according to Business logic>,(v_start_date -v_end_date));

v_res := v_tot/v_tp*decode(v_start_date,v_end_date,<value according to Business logic>,(v_start_date -v_end_date));

SQL> declare a int := 1; b int := 1; c int;
  2  begin
  3    c := decode(a,1,1,0)+b;
  4  end;
  5  /
  c := decode(a,1,1,0)+b;
       *
ERROR at line 3:
ORA-06550: line 3, column 8:
PLS-00204: function or pseudo-column 'DECODE' may be used inside a SQL statement only
ORA-06550: line 3, column 3:
PL/SQL: Statement ignored

--with same dates

SQL> SET SERVEROUTPUT ON
SQL> declare
  2     v_tot          NUMBER;
  3     v_res          NUMBER;
  4     v_tp           NUMBER;
  5     v_start_date   DATE := to_date('01-SEP-2014');
  6     v_end_date     DATE := TO_date('01-SEP-2014');
  7  BEGIN
  8     IF v_start_date = v_end_date
  9     THEN
 10        v_res := 0;
 11         ELSE
 12        v_res := v_tot / v_tp * (v_start_date - v_end_date);
 13     END IF;
 14    DBMS_OUTPUT.PUT_LINE ('Value of v_res'||'-'||to_char(v_res));
 15  EXCEPTION
 16     WHEN ZERO_DIVIDE
 17     THEN
 18        v_res := 0;
 19  END credit_intrest;
 20  /
Value of v_res-0

PL/SQL procedure successfully completed.


--with different dates.

  1  declare
  2     v_tot          NUMBER := 40;
  3     v_res          NUMBER ;
  4     v_tp           NUMBER := 2;
  5     v_start_date   DATE := to_date('30-SEP-2014');
  6     v_end_date     DATE := TO_date('01-SEP-2014');
  7  BEGIN
  8     IF v_start_date = v_end_date
  9     THEN
 10        v_res := 0;
 11         ELSE
 12        v_res := v_tot / v_tp * (v_start_date - v_end_date);
 13     END IF;
 14    DBMS_OUTPUT.PUT_LINE ('Value of v_res'||'-'||to_char(v_res));
 15  EXCEPTION
 16     WHEN ZERO_DIVIDE
 17     THEN
 18        v_res := 0;
 19* END credit_intrest;
SQL> /
Value of v_res-580

PL/SQL procedure successfully completed.