# Rollup Fields

A rollup field is a summary of related fields. Choose a relationship on the same table, choose which field on the related table you need to summarize and then choose how to summarize it.

An example would be if you wanted to calculate the total cost of all projects that each client/company has in the above example. You would add a **rollup** field to the **Company** table with the **projects** relationship we defined earlier. The field to summarize would be **Cost** and you would want to **SUM** the costs, so you get the total sum of costs of all projects associated with a given company.

### Creating a rollup field

* Go to the table you would like to add the rollup field to. In the above example this is the **Company** table.
* Open the table settings sidebar
* Add a new field and choose **Rollup** as the type.
* Choose from one of the multi-relationship fields associated with your table
* Choose the field you would like to summarize on the other table
* Choose which method of aggregation you would like

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### Aggregation Types

| Aggregation Type | Description                                       |
| ---------------- | ------------------------------------------------- |
| SUM              | The sum of all non-empty numeric values           |
| COUNT            | The number of all non-empty values                |
| MAX              | The largest of all the non-empty numeric values   |
| MIN              | The smallest of all the non-empty numeric values  |
| AVERAGE          | The average of all the non-empty numeric values   |
| CONCATENATE      | Join all the text values into a single text value |
| AND              | True if all of the values are true and non-empty  |
| OR               | True if any of the values are true                |

### What about non-numeric types like Durations and Dates?

Aggregation of durations and dates will behave exactly as expected, where the sum of a duration field is the sum of all the times, and the min of a date field is the earliest date