> ## Documentation Index > Fetch the complete documentation index at: https://docs.summation.com/llms.txt > Use this file to discover all available pages before exploring further. # Calculation table > A Summation table defined by a SQL query over your other tables. A **calculation table** is a [Summation table](/features/tables) defined by a **SQL `SELECT`** over your existing tables. Use it for derived datasets — aggregations, rollups, joins, and summaries computed from other tables. **What you can do** * Define the table with a SQL query; its columns come from the query. * **Materialize** it the first time, then **refresh** (synchronize) it to recompute from the latest source data. * Trace its lineage back to the tables it reads from. ## Create a calculation table On the [Tables](/features/tables) page, click **Create → Calculation Table**, then write the `SELECT` in the SQL editor and **Run** it. **Saving does not materialize the result** — it applies the SQL as a column change and leaves the table unmaterialized. Materialize it separately (see **Via the API**) before it can be queried. A calculation table 'DemoCalcTable' showing a data grid (ID, Name, Sex, Age columns) above a SQL editor with 'Run' and a 'Saved' indicator, running SELECT * FROM olympics_event LIMIT 50. Create a calculation table from a SELECT query. Materialize the table so it can be queried. Refresh it from the latest source data.