How It Works
- Add your fact table and its columns. The values you want to analyze, like quantity or unit price. The diagram starts as a sample you can explore; your first table replaces it.
- Add dimensions. Each dimension gets a primary key and its descriptive fields. A matching key column on the fact table is created and linked automatically, so the star shape draws itself.
- Download the diagram. PNG for docs and slides, SVG for wikis and anything that scales. Drag tables to fine-tune the layout first.
What Is a Star Schema?
A star schema is the standard way to organize a database for analytics. One central fact table records the events you measure (sales, clicks, shipments), one row per event: a few numbers plus a key for each dimension. Each surrounding dimension table describes one aspect of those events: who the customer was, which product, which store, on what date. Queries stay fast and simple because every dimension is exactly one join away from the facts, which is why star schemas are the default shape for data warehouses and BI tools.
Star or Snowflake?
A star schema keeps every dimension flat: one table per dimension, one join per query. If your dimensions have their own hierarchy (products belong to categories, stores belong to regions) and you want each level normalized into its own table, use the Snowflake Schema Creator instead. It is this same builder, plus the ability to branch sub-dimensions off any dimension.
Fact Table or Dimension?
A quick rule of thumb: if you would sum it, average it, or count it (these are usually called measures), it belongs on the fact table. If you would filter or group by it, it belongs on a dimension. "Quantity" goes on the fact table; "region" and "product category" are dimension fields.
Keep Working on Your Schema
The star you build here is a real database schema. Open in VibeSchema hands it to the full schema tool, where you can edit the underlying DBML directly, evolve it with AI chat, and organize larger models into views. If you already have a schema in SQL or another format and just want a picture, use ER Diagram to Image instead.
Free, No Sign-Up
The Star Schema Creator is free to use with no account required. Start building above.