SQL and the data warehouse: Tip on date dimensions

SQL and the data warehouse: Tip on date dimensions

In every data warehouse there is a dimension 'date' which starts with the year dimension and drills down to date. Here is an example of an SQL procedure that populates Year, Quarter, Month, Week, Day and Date dimensions. The table names are as follows:

Year - Year_D

Year_Key - SK
The_Year - Int


Quarter - Quarter_D

Quarter_Key - SK
The_Quarter - Int


Month - Month_D

Month_Key - SK
Quarter_Key - Int [Quarter_D.Quarter_key]
The_Month - Int


Week - Week_D

Week_Key - SK
The_Week - Int


Day - Day_D

Day_Key - SK
The_Day - Int


Date - Date_D

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Date_Key - SK
Year_Key - Int [Ref: Year_D.Year_Key]
Month_Key - Int [Ref: Month_D.Month_Key]
Week_Key - Int [Ref: Week_D.Week_Key]
Day_Key - Int [Ref: Day_D.Day_Key]
The_Date - Date


Code:

create procedure Load_Date_Dimension_Sp @year_start int, @year_end int (Full code will be provided in next tip) end

The Procedure can be executed as:

Exec Load_Date_Dimension_Sp 1985, 2005

...which will populate the date dimension for the years 1985 through 2005.

All the syntaxes are based on SQL Server TSQL.

For more information, browse this Learning Guide on Data Quality.

This was first published in April 2002

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