When analyzing data in Power BI, you may need to work with multiple date dimensions. In some cases, you may want to use only a single date dimension table and associate the different date types such as sales date, delivery date, and due date with it. In this blog article, you will learn how to work with a single date dimension table and the USERELATIONSHIP function in DAX to handle different date types.
- Creation of the date dimension table: Create a single date dimension table that contains all the date values you need. This table should contain a unique date field that is used as the primary key. You can also include other information such as months, quarters, and years in the table.
- Linking the fact tables: Link the fact tables that contain sales, delivery, and due dates to the date field in the date dimension table. Make sure you select the correct relationship type option when you define the relationships. For the relationship between the date dimension table and the fact tables with sales data, use the default relationship.
- Creating relationships: In our case, we want to control the relationships between the date dimension table and the fact tables based on the different date types.
- Sales date: The link between the date dimension table and the fact table with sales data should use the default relationship. This will correctly relate the aggregated sales data to the selected sales date.
- Delivery date and due date: Leave the relationships for the delivery date and due date inactive by deactivating the corresponding relationships in Power BI. This will analyze the delivery and due dates regardless of the selected sales date.
- Use of DAX functions: The USERELATIONSHIP function allows you to define explicit relationships between tables and control which relationship is used for specific calculations. Use the USERELATIONSHIP function to define an explicit relationship between the date dimension table and the fact tables containing delivery and due dates. You can use functions such as CALCULATE, SAMEPERIODLASTYEAR, and others to create aggregate values, comparisons, and other analyses based on the different date types.
By using a single date dimension table and the USERELATIONSHIP feature in DAX, you can effectively work with different date types in Power BI. By leaving the relationship for the delivery date and due date inactive, you can perform the desired analyses regardless of the selected sales date.