# Calculated Fields

Calculated Fields (also called Derived Columns) allow you to run queries based on the value of an expression that is calculated from the fields in an event.

This API allows you to list, create, update, and delete Calculated Fields in a dataset or across a whole environment, paralleling the behavior of the Schema tab within a Dataset's or Environment's Settings UI.



## Create a Calculated Field

 - [POST /1/derived_columns/{datasetSlug}](https://api-docs.honeycomb.io/api/calculated-fields/createcalculatedfield.md): Create a Calculated Field (also called a Derived Column). Calculated Fields allow you to run queries based on the value of an expression that is calculated from the fields in an event.

## List all Calculated Fields

 - [GET /1/derived_columns/{datasetSlug}](https://api-docs.honeycomb.io/api/calculated-fields/listcalculatedfields.md): Get all the Calculated Fields (also called Derived Columns) in a dataset or environment. With the ?alias=X query parameter, can return a single Calculated Field by its alias.

## Get a Calculated Field

 - [GET /1/derived_columns/{datasetSlug}/{derivedColumnId}](https://api-docs.honeycomb.io/api/calculated-fields/getcalculatedfield.md)

## Update a Calculated Field

 - [PUT /1/derived_columns/{datasetSlug}/{derivedColumnId}](https://api-docs.honeycomb.io/api/calculated-fields/updatecalculatedfield.md): Update a Calculated Field (also called a Derived Column).

## Delete a Calculated Field

 - [DELETE /1/derived_columns/{datasetSlug}/{derivedColumnId}](https://api-docs.honeycomb.io/api/calculated-fields/deletecalculatedfield.md): Delete a Calculated Field (also called a Derived Column). Note: A Calculated Field used by a SLO, Trigger, or Board cannot be deleted without removing or modifying the SLO, Trigger, or Board first.