For example: productivity figures are only valid if we exclude the bank / public holidays.
Trend analysis reports show representative charts if we exclude weeks with signifcant low values (as a public holiday is in the week).
No RDBMS supports public holidays, not static ones (like New Year), neither will dynamical holidays be supported (like Christian holidays which depend on the date of Easter Day).
Whit Monday is seven weeks after Easter Day and Ascension day is 10 days before Whit Monday.
So we only have to calculate the date of Easter Day. This is a complex calculation as it is originated on a non-accurate version of the Hebrewian calendar. There is a correct formula: Jewish months start on Full Moon. The 14th or 15th day must follow immediately after Full Moon. That's why the decision has been made that Easter Day is the sunday after the first Full Moon after ‘Vernal Equinox’ in spring (the crusification of Jesus). ‘Vernal Equinox’ is on March, 21.
Full Moon before Easter Day is being called: 'Paschal Full Moon'. This conflicts with the date of the real Full Moon (astronomical). As 'Paschal Full Moon' is not variabel, Easter Day can be calculated (hence all other Christian holidays).
I used the following calculation in a stored procedure to calculate the Public Holiday Indicator in a date dimension:
Source: Claus Tøndering, Frequently Asked Questions about Calendars, 25 september 2000
Prerequisites:
CREATE SCHEMA BSM
CREATE TABLE [bsm].[DIM_date]
( [date_id] [int] NOT NULL
, [date] [datetime] NOT NULL
, [day_nr] [int] NOT NULL
, [month_nr] [int] NOT NULL
, [month] [varchar](10) NOT NULL
, [month_key] [int] NOT NULL
, [quarter_nr] [int] NOT NULL
, [quarter] [varchar](2) NOT NULL
, [quarter_key] [int] NOT NULL
, [year] [int] NOT NULL
, [week_nr] [int] NOT NULL
, [week] [varchar](7) NOT NULL
, [week_key] [int] NOT NULL
, [weekday_nr] [int] NOT NULL
, [day] [varchar](9) NOT NULL
, [public_holiday] [varchar](25) NOT NULL
, [weekend] [varchar](1) NOT NULL
, [working_day] [varchar](1) NOT NULL
, [nr_working_days] [int] NOT NULL
, [nr_days] [int] NOT NULL
, CONSTRAINT [PK_DIM_date_id] PRIMARY KEY CLUSTERED
( [date_id] ASC)WITH (IGNORE_DUP_KEY = OFF)
ON [PRIMARY]) ON [PRIMARY]
The function below is needed as SQL SERVER 2005 doesn't support ISO8601 weeknumber (only United States weeknumbers). You do not need this in SQL SERVER 2008. Oracle 9i and higher support it by using the 'IW'-schema.
CREATE FUNCTION [bsm].[ISO8601WeekNr] (@Date datetime)
RETURNS INT
AS
BEGIN
DECLARE @ISO8601Week int
DECLARE @day int
DECLARE @month int
DECLARE @year int
DECLARE @a int
DECLARE @y int
DECLARE @m int
DECLARE @JD int -- Julian day number
DECLARE @d4 int
DECLARE @L int
DECLARE @d1 int
SET @year = YEAR(@Date)
SET @month = MONTH(@Date)
SET @day = DAY(@Date)
SET @a = (14-@month)/12
SET @y = @year +4800 -@a
SET @m = @month + (12*@a) - 3
SET @JD = @day + ( ((153*@m)+2)/5 ) + (365*@y) + (@y/4) - (@y/100) + (@Y/400) - 32045
SET @d4 = (@JD + 31741 - (@JD % 7)) % 146097 % 36524 %1461SET @L = @d4/1460
SET @d1 = ((@d4-@L)%365)+@L
SET @ISO8601Week = (@d1/7) +1
RETURN @ISO8601Week
END
The load script:
CREATE PROCEDURE [bsm].[pLoadDIM_Date] AS
BEGIN
DECLARE @d int -- day counter
DECLARE @date datetime
DECLARE @day_nr int
DECLARE @month varchar(25)
DECLARE @year int
DECLARE @yearvarchar varchar(4)
DECLARE @quarter_nr int
DECLARE @month_nr int
DECLARE @day varchar(9)
DECLARE @g int -- Golden number (-1): Years with the same Golden number have 'New Moon' on the same date
DECLARE @c int -- year/4
DECLARE @h int -- number of days since 'New Moon'
DECLARE @i int -- number of days since March, 21 and 'Paschal Full Maan'
DECLARE @j int -- 'Paschal Full Moon day'
DECLARE @l int -- number of days between March, 21 and Sunday on or before 'Paschal Full Moon' (between -6 and 28)
DECLARE @Easter_month int
DECLARE @Easter int
DECLARE @Easter_date datetime
DECLARE @public_holiday int
DECLARE @x int -- working days counter
DECLARE @y int -- indicator in case week 53 from year x is in year x+1 (100=yes;0=no)
DECLARE @z int -- indicator in case week 1 from year x is in year x-1 (100=yes;0=no)
DECLARE @weekday_nr int
truncate table bsm.dim_date
SET DATEFIRST 1 -- First day of week is Monday (Default is Sunday)
SET @d = -5475 -- First date is current date minus 5475 days
SET @x = 0
WHILE @d <5475
BEGIN
SET @date= DATEADD(dd, @d, GETDATE())
SET @year =YEAR(@date)
SET @yearvarchar = CONVERT(VARCHAR,DATEPART(yy,DATEADD(dd, @d, GETDATE())))
SET @quarter_nr = DATEPART(qq,DATEADD(dd, @d, GETDATE()))
SET @month_nr = DATEPART(mm, DATEADD(dd, @d, GETDATE()))
SET @weekday_nr = DATEPART(dw, DATEADD(dd, @d, GETDATE()))
SET @day_nr = DATEPART(dd, DATEADD(dd, @d, GETDATE()))
SET @day = DATENAME(dw,DATEADD(dd, @d, GETDATE()))
SET @month = DATENAME(mm,DATEADD(dd, @d, GETDATE()))
SET @g = @year%19 SET @c = @year/100SET @h = (@c-(@c/4)-((8*@c+13)/25)+(19*@g)+15)%30
SET @i = @h-((@h/28)*(1-(29/(@h+1)))*((21-@g)/11))
SET @j = (@year+(@year/4)+@i+2-@c+(@c/4))%7SET @l = @i-@j
SET @Easter_month = 3+((@l+40)/44)
SET @Easter = @l+28-31*(@Easter_month/4)
SET @Easter_date = CONVERT(CHAR(10),(CONVERT(DATETIME,CAST(@Easter_month AS CHAR)+'/'+CAST(@Easter AS CHAR)+'/'+CAST(DATEPART(yy, DATEADD(dd,@d, GETDATE())) AS CHAR))),110)
IF @weekday_nr = 6 OR @weekday_nr = 7 OR CONVERT(CHAR(10),@Easter_date,110) = CONVERT(CHAR(10),DATEADD(dd, @d, GETDATE()),110) OR CONVERT(CHAR(10),@Easter_date,110) = CONVERT(CHAR(10),DATEADD(dd, @d-1, GETDATE()),110) OR CONVERT(CHAR(10),@Easter_date,110) = CONVERT(CHAR(10),DATEADD(dd, @d-49, GETDATE()),110) OR CONVERT(CHAR(10),@Easter_date,110) = CONVERT(CHAR(10),DATEADD(dd, @d-50, GETDATE()),110) OR CONVERT(CHAR(10),@Easter_date,110) = CONVERT(CHAR(10),DATEADD(dd, @d-39, GETDATE()),110) OR (@day_nr= 1 AND @month_nr = 1) OR (@day_nr = 30 AND @month_nr = 4) OR (@day_nr = 25 AND @month_nr = 12) OR (@day_nr = 26 AND @month_nr = 12)
SET @public_holiday = 1 ELSE select @public_holiday = 0
IF @public_holiday =1 or @weekday_nr in(6,7)
SET @x = @x ELSE
SET @x =@x+1
IF bsm.ISO8601weekNr(CONVERT(CHAR, (DATEADD(dd, @d, GETDATE())),101)) >51 and @month_nr = 1
SET @y=100 ELSE SET @y=0 -- if a week belongs party to the next year (2004.53 belongs party to 2005) set indicator on 100 so -- if you subtract 100 of 200553, week 200553 is still week 200453.
IF bsm.ISO8601weekNr(CONVERT(CHAR, (DATEADD(dd, @d, GETDATE())),101)) =1 and @month_nr = 12
SET @z=100 ELSE SET @z=0 -- if a week is in last year (first week of 2004 belongs partly to 2003) set indicator on 100 so -- if you add 100 to 200301 week 200301, week 200301 is still 200401
INSERT INTO bsm.dim_date
SELECT ((DATEPART(yy, DATEADD(dd, @d, GETDATE())) * 100) + DATEPART(mm,DATEADD(dd, @d, GETDATE()))) * 100 + @day_nr AS date_id
, CAST(CONVERT(VARCHAR, @date, 111) AS DATETIME) as date
, @day_nr AS day_nr
, DATEPART(mm, DATEADD(dd, @d, GETDATE())) AS month_nr
, @month AS month
, (CAST(DATEPART(yy, DATEADD(dd, @d, GETDATE())) AS VARCHAR)*100)+ DATEPART(mm, DATEADD(dd, @d, GETDATE())) AS month_key
, DATEPART(qq,DATEADD(dd, @d, GETDATE())) AS quarter_nr
, 'Q'+CONVERT(VARCHAR,DATEPART(qq,DATEADD(dd, @d, GETDATE()))) as quarter
, (CAST(DATEPART(yy, DATEADD(dd, @d, GETDATE())) AS VARCHAR)*100)+ DATEPART(qq,DATEADD(dd, @d, GETDATE())) AS quarter_key
, @year AS year_nr
, bsm.ISO8601weekNr(CONVERT(CHAR, (DATEADD(dd, @d, GETDATE())),101)) AS week_nr
, 'Week '+CONVERT(VARCHAR,bsm.ISO8601weekNr(CONVERT(CHAR, (DATEADD(dd, @d, GETDATE())),101))) AS week
, (CAST(DATEPART(yy, DATEADD(dd, @d, GETDATE())) AS VARCHAR)*100)+CAST (bsm.ISO8601weekNr(CONVERT(CHAR, (DATEADD(dd, @d, GETDATE())),101)) AS VARCHAR)-@y+@z AS week_key
, @weekday_nr AS weekday_nr
, @day AS day
, CASE WHEN CONVERT(CHAR(10),@Easter_date,110) = CONVERT(CHAR(10),DATEADD(dd, @d, GETDATE()),110) THEN 'Easter Day'
WHEN CONVERT(CHAR(10),@Easter_date,110) = CONVERT(CHAR(10),DATEADD(dd, @d-1, GETDATE()),110) THEN'Easter Monday'
WHEN CONVERT(CHAR(10),@Easter_date,110) = CONVERT(CHAR(10),DATEADD(dd, @d-49, GETDATE()),110) THEN 'Whit Sunday'
WHEN CONVERT(CHAR(10),@Easter_date,110) = CONVERT(CHAR(10),DATEADD(dd, @d-50, GETDATE()),110) THEN 'Whit Monday'
WHEN CONVERT(CHAR(10),@Easter_date,110) = CONVERT(CHAR(10),DATEADD(dd, @d-39, GETDATE()),110) THEN 'Ascension day'
WHEN @day_nr= 1 AND @month_nr = 1 THEN 'New Year-s Day' WHEN @day_nr = 30 AND @month_nr = 4 THEN 'Dutch Queen-s Day'
WHEN @day_nr = 25 AND @month_nr = 12 THEN 'Christmas Day' WHEN @day_nr = 26 AND @month_nr = 12 THEN 'Boxing Day' ELSE '-'
END AS public_holiday
, CASE WHEN @weekday_nr in(6,7) THEN 'Y' ELSE 'N' END AS weekend
, CASE WHEN @public_holiday = 1 OR @weekday_nr in(6,7) THEN 'N' ELSE 'Y' END AS working_day
, @x AS nr_working_days
, @d+5476 AS nr_days
SET @d = @d + 1
END
END
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