Date Dimension
There are 3 sections in this script:
1) Create the Date Dimension table
2) Load Data for a specified date range. Supply start and end dates to the variables
@startDate and @EndDate.
3) Update the column "LastDayOfMonth", which I find very useful while doing data analysis.
I use a function called "fnGetLastDayOfMonth" to obtain the last day of a given month.
You need to run the script in the listed order.
Note that the last three columns prefixed with the word "Holiday" are not populated with this script. These fields can be populated at the beginning of each year as you go or you can bulk update with a pre-populated "Holiday" table. I hope you find this script handy.
--Listing 1
------------
--drop table DimDate
if object_id('DimDate') IS NOT NULL
drop table DimDate
create table DimDate(
DateKey int NOT NULL
,DayOfMonth tinyint NULL
,MonthOfYear tinyint NULL
,[Year] smallint NULL
,[DayOfWeek] varchar(15) NULL
,WeekOfYear tinyint NULL
,[DayOfYear] smallint NULL
,[MonthName] varchar(20) NULL
,[Quarter] tinyint NULL
,QuarterName varchar(20) NULL
,IsLastDayOfMonth char(1) NULL
,IsHoliday char(1) NULL
,HolidayName varchar(50) NULL
,HolidayDescription varchar(150) NULL
)
GO
--Listing 2
----------
declare @startDate as datetime,@enddate as datetime
--initialize
set @startDate = '01/01/2007'
set @enddate = '01/01/2009'
while @startDate<@enddate
begin
insert into DimDate(
DateKey
,[DayOfMonth]
,MonthOfYear
,[Year]
,[DayOfWeek]
,WeekOfYear
,[DayOfYear]
,[MonthName]
,[Quarter]
,QuarterName)
select cast(convert(varchar(8),@startdate,112) as int)
,day(@startdate)
,Month(@startdate)
,Year(@startdate)
,datename(weekday,@startdate) as WeekDay
,datename(week,@startdate) as Week
,datename(dayOfYear,@startdate) as dayOfYear
,datename(month,@startdate) as MonthName
,datename(quarter,@startdate) as Quarter
,CASE datename(quarter,@startdate)
WHEN 1 THEN 'First Quarter'
WHEN 2 THEN 'Second Quarter'
WHEN 3 THEN 'Third Quarter'
WHEN 4 THEN 'Fourth Quarter'
END AS QuarterName
set @startDate = @startDate +1
end
GO
--Listing 3
------------
CREATE FUNCTION fnGetLastDayOfMonth
-- Input parameters
(
@Anydate datetime
)
RETURNS datetime AS
/********************************************************************
Returns the last day of the month (extracted from the date passed)
*********************************************************************/
BEGIN
-- add one month to the datepassed
SET @Anydate = DATEADD(m,1,@Anydate)
RETURN DATEADD(d,-datepart(d,@Anydate),@Anydate)
END
GO
--Update the column IsLastDayOfMonth
UPDATE
DimDate
SET
IsLastDayOfMonth = CASE WHEN dbo.fnGetLastDayOfMonth(cast(DateKey as varchar(10)))= Cast(Cast(DateKey as varchar(10)) as datetime) THEN 'Y'
ELSE 'N' END
GO
select * from DimDate
