Load time dimension tables

• 3 minutes

Time dimension tables store a record for each time interval based on the grain by which you want to aggregate data over time. For example, a time dimension table at the date grain contains a record for each date between the earliest and latest dates referenced by the data in related fact tables.

The following code example shows how you can generate a sequence of time dimension values based on a date grain.

-- Create a temporary table for the dates we need
CREATE TABLE #TmpStageDate (DateVal DATE NOT NULL)

-- Populate the temp table with a range of dates
DECLARE @StartDate DATE
DECLARE @EndDate DATE
SET @StartDate = '2019-01-01'
SET @EndDate = '2023-12-31'
DECLARE @LoopDate = @StartDate
WHILE @LoopDate <= @EndDate
BEGIN
    INSERT INTO #TmpStageDate VALUES
    (
        @LoopDate
    )
    SET @LoopDate = DATEADD(dd, 1, @LoopDate)
END

-- Insert the dates and calculated attributes into the dimension table
INSERT INTO dbo.DimDate
SELECT CAST(CONVERT(VARCHAR(8), DateVal, 112) as INT), -- date key
    DateVal, --date alt key
    Day(DateVal) -- day number of month
    --,  other derived temporal fields as required
FROM #TmpStageDate
GO

--Drop temporary table
DROP TABLE #TmpStageDate

As the data warehouse is populated in the future with new fact data, you periodically need to extend the range of dates related time dimension tables.