Re: About Date Functions

Question

Vansuypeene Laurent wrote:
>
Hello Forte Users,
I'm looking for a function that returns the number of the week
in the year (from 1 to 53) and the number of the day in the year (from 1
to 365).
Has anyone written it ?
Thanks
L. VANSUYPEENE
e-mail : [email protected]
Try this code for day of year
DayOfYear :
-------------------------START OF CODE--------------------------------
dtd1,dtd2 : DateTimeData = new;
df: dateformat = new(template = 'd/m');
-- Set dtd1 to 1 januari
dtd1 = df.decodedate('1/1');
dtd2.SetCurrent();
intd : IntervalData = new;
intd.SetUnit(months = dtd2.GetUnit(DR_MONTH) - 1,
days = dtd2.GetUnit(DR_DAY));
-- Normalize : calculate days starting from dtd1
intd.Normalize(dtd1);
return intd.GetUnit(DR_DAY);
-------------------------END OF CODE--------------------------------
Try this code for week of year :
Week of Year :
-------------------------START OF CODE--------------------------------
OFFSET_WEEKDAY : Integer = 6;
THURSDAY : Integer = 4;
wd : DateTimeData;
jul_31dec : Integer;
wd_1jan : Integer;
jul_mon1 : Integer;
yr : Integer;
mn : Integer;
dy : Integer;
jul : Integer;
weeknr : Integer;
month_cm_365 : Array of IntegerData = new;
month_cm_365[1] = IntegerData(value=0);
month_cm_365[2] = IntegerData(value=31);
month_cm_365[3] = IntegerData(value=59);
month_cm_365[4] = IntegerData(value=90);
month_cm_365[5] = IntegerData(value=120);
month_cm_365[6] = IntegerData(value=151);
month_cm_365[7] = IntegerData(value=181);
month_cm_365[8] = IntegerData(value=212);
month_cm_365[9] = IntegerData(value=243);
month_cm_365[10] = IntegerData(value=273);
month_cm_365[11] = IntegerData(value=304);
month_cm_365[12] = IntegerData(value=334);
month_cm_366 : Array of IntegerData = new;
month_cm_366[1] = IntegerData(value=0);
month_cm_366[2] = IntegerData(value=31);
month_cm_366[3] = IntegerData(value=60);
month_cm_366[4] = IntegerData(value=91);
month_cm_366[5] = IntegerData(value=121);
month_cm_366[6] = IntegerData(value=152);
month_cm_366[7] = IntegerData(value=182);
month_cm_366[8] = IntegerData(value=213);
month_cm_366[9] = IntegerData(value=244);
month_cm_366[10] = IntegerData(value=274);
month_cm_366[11] = IntegerData(value=305);
month_cm_366[12] = IntegerData(value=335);
wd = new;
wd.SetValue(dateTimeData().SetCurrent().Value);
yr = wd.GetUnit(DR_YEAR);
mn = wd.GetUnit(DR_MONTH);
dy = wd.GetUnit(DR_DAY);
-- always needed : the julian date of 31 december of the
-- previous year
jul_31dec = 365 * (yr - 1) + (yr - 1) / 4
- (yr - 1) / 100
+ (yr - 1) / 400;
begin
-- calculate the julian date
yd : Integer; -- days in current year
yr_366 : Boolean;
yr_366 = ( (yr % 400) = 0 ) OR
( ((yr % 4) = 0) AND ((yr % 100) <> 0));
if yr_366 then
yd = month_cm_366[mn].Value + dy;
else
yd = month_cm_365[mn].Value + dy;
end if;
jul = yd + jul_31dec;
end;
wd_1jan = (jul_31dec + 1 + OFFSET_WEEKDAY) % 7 + 1;
if ( wd_1jan <= THURSDAY) then
jul_mon1 = jul_31dec + 1 - wd_1jan + 1;
else
jul_mon1 = jul_31dec + 1 - wd_1jan + 1 + 7;
end if;
weeknr = (jul - jul_mon1 + 7) / 7;
-- Treat the special cases : week 0 and 53
if ( weeknr = 0 ) then
-- calculate the julian date of the first monday of 2
-- years ago and use this to calculate the week number
jul_31dec : Integer = 365 * (yr-2)
+ (yr-2) / 4
- (yr-2) / 100
+ (yr-2) / 400;
wd_1jan = (jul_31dec + 1 + OFFSET_WEEKDAY) % 7 + 1;
if ( wd_1jan <= THURSDAY ) then
jul_mon1 = jul_31dec + 1 - wd_1jan + 1;
else
jul_mon1 = jul_31dec + 1 - wd_1jan + 1 + 7;
end if;
weeknr = (jul - jul_mon1 + 7) / 7;
end if;
if ( weeknr = 53 ) then
-- week 53 of this year or week 1 of the next year
-- calculate the weekday of january 1st of the next year
-- and decide week 1 or 53
jul_31dec : Integer = 365 * yr
+ yr / 4
- yr / 100
+ yr / 400;
wd_1jan = (jul_31dec + 1 + OFFSET_WEEKDAY) % 7 + 1;
if ( wd_1jan <= THURSDAY ) then
weeknr = 1;
end if;
end if;
return weeknr;
-------------------------END OF CODE--------------------------------
Thanks to Franky De Lamper of Cap Gemini
Steven Arijs
[email protected]

Answer 1

e.g.
SQL> ed
Wrote file afiedt.buf
  1  with t as (select to_date('15-may-1982', 'dd-mon-yyyy') as dt from dual union all
  2             select to_date('24-may-1982', 'dd-mon-yyyy') from dual)
  3  -- END OF TEST DATA
  4  select dt,
  5         round(dt,'mm') as rnd_date,
  6         trunc(dt,'mm') as trnc_date
  7* from t
SQL> /
DT          RND_DATE    TRNC_DATE
15-MAY-1982 01-MAY-1982 01-MAY-1982
24-MAY-1982 01-JUN-1982 01-MAY-1982
SQL>Note: In case you didn't realize, rounding will round dates as with numbers (up or down), and you should use TRUNC if you want to remove the day portion (i.e. truncate to the start of the month)