---
title: Query language functions reference
sidebar_label: Query language functions
---

<!--TODO: Link to the start of the series for https://github.com/deephaven/deephaven.io/issues/1455-->

Deephaven's query language has many functions that are automatically imported for use. This reference page lists the most popular classes whose methods are automatically imported and can be used within query strings.

The full list of classes, packages, and methods that are imported is defined in the [QueryLibraryImportsDefaults Java class](https://github.com/deephaven/deephaven-core/blob/main/engine/table/src/main/java/io/deephaven/engine/table/lang/impl/QueryLibraryImportsDefaults.java).

## Packages

- [`io.deephaven.function`](/core/javadoc/io/deephaven/function/package-summary.html)

## Classes

- [`io.deephaven.time.DateTimeUtils`](/core/javadoc/io/deephaven/time/DateTimeUtils.html)

## Related documentation

- [How to use automatically imported query language functions](../../../how-to-guides/built-in-functions.md)