Building a Time Dimension Copyright © 2001 by Michael A. Mina.

Building a Time Dimension

Copyright © 2001 by Michael A. Mina

Copyright © 2001 by Michael A. Mina 2

Create (manually or otherwise) one table listing the digits 0 through 9.


SELECT 1000*A.Digit+100*B.Digit+10*C.Digit+D.Digit AS DateKey, DateAdd("d",1000*A.Digit+100*B.Digit+10*C.Digit+D.Digit,#01/01/1990#) AS DateValue INTO DateValuesFROM Digits AS A, Digits AS B, Digits AS C, Digits AS DORDER BY 1;

Write a cross join query to create a Cartesian product of the table with itself four times.

Our SELECT statement will use the Cartesian product to create the integers 0 through 10,000.

The DateAdd function will add these integers to a starting date (in this case, 1/1/1990).

Different databases may use a different function to add integers to dates.


SELECT DateKey, DateValue, Day(DateValue) AS Day, Month(DateValue) AS Month, Int((Month(DateValue)+2)/3) AS Quarter, Year(DateValue) AS Year INTO TimeDimensionFROM DateValues;

Create a Time dimension table using the previous table.

Use the row functions provided by your database to add the information you need.

Remember to create a primary key on the Time dimension table.

Building a Time Dimension Copyright © 2001 by Michael A. Mina.

Documents

Transcript of Building a Time Dimension Copyright © 2001 by Michael A. Mina.