Database Relations 101

Relations transform Notion from isolated tables into a connected, intelligent system. A Relation links items between two databases. This is the foundation of relational database design — what makes Notion far more powerful than a spreadsheet.

Creating Your First Relation

  1. Add a new property in your Tasks database.
  2. Choose "Relation" as the property type.
  3. Select "Projects" as the target database.
  4. Name clearly: "Project" on Tasks, "Tasks" on Projects.

Each task links to a project. Click any project to see all its tasks. From any task, navigate to its parent project. Two-way connection, no duplication.

Rollups: Aggregating Related Data

A Rollup pulls data from related items and performs calculations: Count, Sum, Average, Median, Min, Max, Range, Earliest/Latest date. After creating a Relation, add a Rollup to aggregate data from the linked database.

Practical Examples

Task Progress Tracker

Rollup the average Progress of related tasks. Shows project completion at a glance — no manual updates needed.

Budget vs. Actual

Rollup sum of expenses. Formula: prop("Budget") - prop("Actual Spend Rollup"). Positive = under budget.

Client Dashboard

Rollup count of active projects and sum of revenue per client. Shows engagement and value simultaneously.

Formula + Rollup Combinations

if(prop("Task Progress Rollup") == 100, "Complete", if(prop("Task Progress Rollup") > 0, "In Progress", "Not Started"))

Best Practices

  • Name relations clearly — "Project" not "Related to."
  • Limit depth to 2 levels (A→B→C).
  • Use descriptive Rollup names — "Avg Task Progress."
  • Archive, never delete Relations — deleting removes all connections permanently.