Simplify the select query to get single record

Question

Please let me know what is wrong with my query.
Max(p_received_date) is returning null columns too. But i need to have only null record per period, if there is date and null record for the same billing then return the date record. please check november and september records. september should return only 09/13/10 record but it is returning null record too. please help to get expected out put.
SELECT DISTINCT B_BILLING_KEY,
to_char(to_date('01/'||trim(substr(B_REPORT_PERIOD,5,2))||'/'||
trim(substr(B_REPORT_PERIOD,1,4)),'DD/MM/YYYY'),'Month YYYY') Billing,
B_company_id company,
sum((nvl(T.B_ORG_SURCH_AMOUNT,0)+nvl(T.B_ORG_PI_AMOUNT,0))-(nvl(T.P_AMOUNT,0))) "PeriodBalance",
Max(to_char(P_RECEIVED_DATE,'MM/DD/YY')) LastPaymentDate,
decode(sign(
(nvl(T.B_ORG_SURCH_AMOUNT,0)+nvl(T.B_ORG_PI_AMOUNT,0))-(nvl(T.P_AMOUNT,0))), 1,'Yes','No') Outs
FROM mv_program_dict P, tuff_balance_view T WHERE
b_company_id = 'U-7052-C' group by B_REPORT_PERIOD,B_company_id,B_BILLING_KEY,B_ORG_SURCH_AMOUNT,
B_ORG_PI_AMOUNT,P_AMOUNT
order by B_BILLING_KEY desc
Actual
Billing key Billing company periodbalance lastpayment date outs
110631534073 November 2010 U-7052-C 270 Yes
110631534073 November 2010 U-7052-C 690 Yes
110631534073 November 2010 U-7052-C 66 Yes
110461533197 October 2010 U-7052-C 4740 Yes
110461533197 October 2010 U-7052-C 27000 Yes
110461533197 October 2010 U-7052-C 0 No
110251532527 September 2010 U-7052-C 0 09/13/10 No
110251532527 September 2010 U-7052-C 0 No
110251532527 September 2010 U-7052-C -18 09/13/10 No
110251532484 August 2010 U-7052-C 0 09/13/10 No
110251532484 August 2010 U-7052-C 2001 09/13/10 Yes
110251532484 August 2010 U-7052-C 0 No
Expectedoutput(need only following columns)Outs is outstanding balance
Billing key Billing company l astpayment date outs
110631534073 November 2010 U-7052-C Yes
110461533197 October 2010 U-7052-C Yes
110251532527 September 2010 U-7052-C 09/13/10 No
110251532484 August 2010 U-7052-C 09/13/10 YES
By using below query i am getting all output as NO. HOw to modify this query.
SELECT company,
billing,LastPaymentDate,
CASE
WHEN SUM (DECODE (outs, 'YES', 1, 0)) > 0 THEN 'YES'
ELSE 'NO'
END Outstanding
FROM (
SELECT DISTINCT B_BILLING_KEY,
to_char(to_date('01/'||trim(substr(B_REPORT_PERIOD,5,2))||'/'||
trim(substr(B_REPORT_PERIOD,1,4)),'DD/MM/YYYY'),'Month YYYY') Billing,
B_company_id company,
sum((nvl(T.B_ORG_SURCH_AMOUNT,0)+nvl(T.B_ORG_PI_AMOUNT,0))-(nvl(T.P_AMOUNT,0))) "PeriodBalance",
Max(to_char(P_RECEIVED_DATE,'MM/DD/YY')) LastPaymentDate,
decode(sign(
(nvl(T.B_ORG_SURCH_AMOUNT,0)+nvl(T.B_ORG_PI_AMOUNT,0))-(nvl(T.P_AMOUNT,0))), 1,'Yes','No') Outs
FROM mv_program_dict P, tuff_balance_view T WHERE
b_company_id = 'U-7052-C' group by B_REPORT_PERIOD,B_company_id,B_BILLING_KEY,B_ORG_SURCH_AMOUNT,
B_ORG_PI_AMOUNT,P_AMOUNT
order by B_BILLING_KEY desc)
GROUP BY company, billing,LastPaymentDate;
Note:in the actual out put max(lastpayment date) is returing null values. if there is any date in one billing return that date only remove null example is september. in september it should return only 09/13/10 this date not null date. but if there is no other within one biling then consider that as null example november..
Thanks,
v

Answer 1

Another solution is setting NLS_SORT to CI - case insensitive (or whatever_your_language_is_CI) and NLS_COMP to ANSI:
SQL> with t as (
  2             select 'HARI' name from dual union all
  3             select 'Hari' name from dual union all
  4             select 'HaRi' name from dual
  5            )
  6  select  *
  7    from  t
  8    where name = 'hArI'
  9  /
no rows selected
SQL> alter session set nls_sort = binary_ci
  2  /
Session altered.
SQL> alter session set nls_comp=ansi
  2  /
Session altered.
SQL> with t as (
  2             select 'HARI' name from dual union all
  3             select 'Hari' name from dual union all
  4             select 'HaRi' name from dual
  5            )
  6  select  *
  7    from  t
  8    where name = 'hArI'
  9  /
NAME
HARI
Hari
HaRi
SQL> SY.