Forms 6i Bad first day of week

Question

Hello,
Please help me
We have oracle form 6i application in our organization, in the past we had the same app but the database was 9i (9.2.0.1) and we migrate the database to 10g (10.2.0.1) with the same NLS parameters, the problem is there are forms calculating the first day of the week based in the query :
SELECT TO_CHAR(TO_DATE('03/01/2005','DD/MM/YYYY'),'D')
FROM
DUAL;
this query through the sqlplus (ORACLE_HOME form 6i) return 2
using sqltools client with and without tnsname return 2
in the server using sqlplus with and without tnsname return 2
but when rhe form insert data into data base insert a wrong value the Monday(2) insert as Sunday(1)
INSTANCE
PARAMETER     VALUE
NLS_LANGUAGE     AMERICAN
NLS_TERRITORY     AMERICA
NLS_SORT
NLS_DATE_LANGUAGE
NLS_DATE_FORMAT
NLS_CURRENCY
NLS_NUMERIC_CHARACTERS
NLS_ISO_CURRENCY
NLS_CALENDAR
NLS_TIME_FORMAT
NLS_TIMESTAMP_FORMAT
NLS_TIME_TZ_FORMAT
NLS_TIMESTAMP_TZ_FORMAT
NLS_DUAL_CURRENCY
NLS_COMP
NLS_LENGTH_SEMANTICS     BYTE
NLS_NCHAR_CONV_EXCP     FALSE
DATABASE
PARAMETER     VALUE
NLS_LANGUAGE     AMERICAN
NLS_TERRITORY     AMERICA
NLS_CURRENCY     $
NLS_ISO_CURRENCY     AMERICA
NLS_NUMERIC_CHARACTERS     .,
NLS_CHARACTERSET     WE8ISO8859P1
NLS_CALENDAR     GREGORIAN
NLS_DATE_FORMAT     DD-MON-RR
NLS_DATE_LANGUAGE     AMERICAN
NLS_SORT     BINARY
NLS_TIME_FORMAT     HH.MI.SSXFF AM
NLS_TIMESTAMP_FORMAT     DD-MON-RR HH.MI.SSXFF AM
NLS_TIME_TZ_FORMAT     HH.MI.SSXFF AM TZR
NLS_TIMESTAMP_TZ_FORMAT     DD-MON-RR HH.MI.SSXFF AM TZR
NLS_DUAL_CURRENCY     $
NLS_COMP     BINARY
NLS_LENGTH_SEMANTICS     BYTE
NLS_NCHAR_CONV_EXCP     FALSE
NLS_NCHAR_CHARACTERSET     AL16UTF16
NLS_RDBMS_VERSION     10.2.0.1.0
CLIENTES FORMS REGEDIT KEY NLS_LANG
LATIN AMERICAN SPANISH_AMERICA.WE8ISO8859P1
Thank foy your help, and sorry for my English

Answer 1

Gerd, that German Weekday function is nice. I looked it over and tried out various things, especially those suggested by JWH and Laurent Schneider in the comments. Using JWH's method, I came up with this function below.
I have tried it out with every NLS_Territory setting I can find, and it works everywhere:
  Function week_day_standard(d in date) return number is begin
  -- This function returns a value from 1 to 7 identifying
  -- the day of the week, where Monday is always 1, and
  -- Sunday is 7.
  -- In Oracle, depending on the NLS_Territory setting,
  --   different days of the week are 1.
  -- Examples:
  --   U.S., Canada, Monday = 2;  Most European countries, Monday = 1;
  --   Most Middle-Eastern countries, Monday = 3.
  --   For Bangladesh, Monday = 4.
    Return 1 + mod(to_number(to_char(d,'J')),7);
  End week_day_standard;And here is a SQL Plus script I used to verify the function:
clear screen
Declare
  S  varchar2(1);
  M  varchar2(1);
  Function week_day_standard(d in date) return number is begin
  -- This function returns a value from 1 to 7 identifying
  -- the day of the week, where Monday is always 1, and
  -- Sunday is 7.
  -- In Oracle, depending on the NLS_Territory setting,
  --   different days of the week are 1.
  -- Examples:
  --   U.S., Canada, Monday = 2;  Most European countries, Monday = 1;
  --   Most Middle-Eastern countries, Monday = 3.
  --   For Bangladesh, Monday = 4.
    Return 1 + mod(to_number(to_char(d,'J')),7);
  End week_day_standard;
  procedure go3 (d1 date) is
   d date := d1;
  begin
    loop
      d := d+1;
      DBMS_Output.Put_Line('          '
       ||       to_char(d,'Dy, mm-dd-yyyy D')
       ||'  '|| to_char( d+1-trunc(d,'iw') )
       ||''  || week_day_standard(d)
       ||''  || to_char(1+mod(to_number(to_char(d,'J')),7))
       ||'  '|| to_char(trunc(d,'iw'),'mm-dd-yyyy')  );
      exit when to_char(d,'mmdd')='0104';
    end loop;
    DBMS_Output.Put_Line(' ');
  end go3;
  procedure go2 is begin
    go3(DATE'2004-12-26');
    go3(DATE'2005-12-25');
    go3(DATE'2006-12-24');
    go3(DATE'2007-12-30');
    go3(DATE'2008-12-28');
    go3(DATE'2009-12-27');
  end go2;
  procedure go(T varchar2) is begin
    execute immediate('alter session set nls_territory='''||T||'''');
    S := TO_CHAR(TO_DATE('07/20/2008','MM/dd/YYYY'),'D'); -- sunday, July 20, 2008
    M := TO_CHAR(TO_DATE('07/21/2008','MM/dd/YYYY'),'D'); -- Monday, July 21, 2008
    DBMS_Output.Put_Line('  '||S ||'   '||M||'   '||rpad(T,16) );
    go2;
  End go;
Begin
  DBMS_Output.Put_Line(chr(10)||' Sun Mon Territory' || chr(10)||' --- --- -----------');
  Go('UNITED KINGDOM');
  Go('MOROCCO');
  Go('BANGLADESH');
  Go('AMERICA');
End;
/