Date dimension has been discussed quite a lot on the Internet and you can find lots of valuable articles around it here and there. But what if you need to analyse your data in time level? A customer has a requirement to analyse their data in Minutes level. This means that the granularity of the fact table would be at minute level. So, if they store the data in their transactional database in seconds level, then we need to aggregate that data to minutes level. I don’t want to go there, just bear in mind that the granularity of your fact table is something that you must think about at the very first steps. In most cases, if not all cases, you’d be better to have a separate Time dimension. Then you need to have a TimeID or Time column in your fact table to be able to create a relationship between the Time dimension and the fact table. In this post I show you two ways to create Time dimension in Power BI:
- Creating Time dimension with DAX
- Creating Time dimension with Power Query (M)
Alternatively, you can take care of the Time dimension in the source system like SQL Server. Continue reading and you’ll find a T-SQL codes as complementary.
The techniques that I explain here can be done in SSAS Tabular model and Azure Analysis Services as well.
To follow the steps of building the test model you need to have:
- Power BI Desktop: Download the latest version from here
- A sample fact table containing time or datetime. I modified FactInternetSales from AdventureWorksDW and made it available for you to download in Excel format (find the download link at the bottom of the post)