Week of the year

[torturedmind]

Here is a small SQL showing that week 1 of the year starts with Jan. 1 and Sunday is day 1 of a week.

SELECT
    a.d dDate,
    TO_CHAR(a.d, 'Dy') cDay,
    TO_NUMBER(TO_CHAR(a.d, 'd')) nDay,
    TO_NUMBER(TO_CHAR(a.d, 'ww')) nWeek,
    TO_NUMBER(TO_CHAR(a.d, 'ww')) +
        CASE WHEN TO_CHAR(a.d, 'ww') = TO_CHAR((a.d - TO_NUMBER(TO_CHAR(a.d, 'd'))), 'ww')
            THEN 1
            ELSE 0
        END nCorrectWeek
    FROM
        (SELECT
            TRUNC(SYSDATE, 'y') - 1 + ROWNUM d
            FROM All_Objects
            WHERE ROWNUM <= ADD_MONTHS(TRUNC(SYSDATE, 'y'), 12) - TRUNC(SYSDATE, 'y')) a;

And here is the function version that accepts dates:

create or replace function THWW 
(
    Date_Entry in date 
)   return number  is

    WWNum number;

begin
    WWNum := TO_NUMBER(TO_CHAR(Date_Entry, 'ww')) +
        CASE WHEN TO_CHAR(Date_Entry, 'ww') = TO_CHAR((Date_Entry - TO_NUMBER(TO_CHAR(Date_Entry, 'd'))), 'ww')
            THEN 1
            ELSE 0
        END;

    return WWNum;
end THWW;

My question is, knowing that "IW" is the standard, are we the only ones (I mean, the company I work for) that requires such non-standard week numbering? My apologies but it confuses me how they designed the logic of IW and WW.

kilroy
philippines

"Once a king, always a king. But being a knight is more than enough."