Notion Formula Tutorial: Group Rollup Results in Database

This question comes from a reader of the Notion course. It has been organized and shared here. If you encounter similar issues while using Notion, feel free to leave a comment.

Background

I received an interesting question in the Notion course comment section: "Can you group Rollup results?" This question arose while practicing the PARA methodology, with the following context:

The Task database is related to the Project database
The Project database is related to the Area database
The Area database contains several areas, such as Area A, Area B, and Area C
These areas are categorized into three groups — Work, Study, and Life — using a Select property

The question is: after assigning a tag like Work to "Area A" in the Area database, can the projects related to that area, and the tasks related to those projects, also automatically receive the Work tag? If so, it would be possible to share the same grouping standard (Group) across all three databases, as shown below:

The answer is yes, but we cannot directly group Rollup results. Instead, we need to combine Rollup with Formula.

Solution Steps

Step 1: Add a Formula in the Project Database

Add a Formula property in the Project database. Use the map function to look up the Select property value of the Area related to each Project. Since map returns a list (array format), which also cannot be grouped directly, you need to add a format function to convert the list into plain text. This approach of passing properties across databases can also be used for property inheritance:

This way, Group can directly group by the plain text output from the Formula:

Step 2: Add a Rollup and Formula in the Task Database

In the Task database, create a Rollup on the Project relation to look up the Area associated with each Project:

Then add a Formula property. Use the map function to query the Area values retrieved by the Rollup, and use the format function to convert the result into plain text:

Now you can also group by the Formula:

Step 3: Verify Automatic Sync

Now, when you change a Select value in the Area database, the related Tasks and Projects will automatically update and regroup:

Latest update: If your Rollup outputs currency, percentage, or other numeric results, Notion now supports number formats and decimal places directly, so you no longer need extra formulas just for display formatting.