---
title: Work with null types
description: The null type represents a missing or unknown value. Learn how to work with null types in Flux.
url: https://docs.influxdata.com/flux/v0/data-types/basic/null/
estimated_tokens: 2005
product: Flux
version: v0
---

# Work with null types

The **null type** represents a missing or unknown value.

**Type name**: `null`

-   [Null syntax](#null-syntax)
-   [Check if a column value is null](#check-if-a-column-value-is-null)
-   [Include null values in an ad hoc stream of tables](#include-null-values-in-an-ad-hoc-stream-of-tables)

## Null syntax

Null types exist in [columns](/flux/v0/get-started/data-model/#column) of other [basic types](/flux/v0/data-types/basic/). Flux does not provide a literal syntax for a *null* value, however, you can use [`debug.null()`](/flux/v0/stdlib/internal/debug/null/) to return a null value of a specified type.

```js
import "internal/debug"

// Return a null string
debug.null(type: "string")

// Return a null integer
debug.null(type: "int")

// Return a null boolean
debug.null(type: "bool")
```

An empty string (`""`) **is not** a *null* value.

## Check if a column value is null

In functions that iterate over rows (such as [`filter()`](/flux/v0/stdlib/universe/filter/) or [`map()`](/flux/v0/stdlib/universe/map/)), use the [`exists` logical operator](/flux/v0/spec/operators/#logical-operators) to check if a column value is *null*.

##### Filter out rows with null values

```js
data
    |> filter(fn: (r) => exists r._value)
```

##### Given the following input data:

| _time | _value |
| --- | --- |
| 2021-01-01T00:00:00Z | 1.2 |
| 2021-01-01T02:00:00Z |  |
| 2021-01-01T03:00:00Z | 2.5 |
| 2021-01-01T04:00:00Z |  |

##### The example above returns:

| _time | _value |
| --- | --- |
| 2021-01-01T00:00:00Z | 1.2 |
| 2021-01-01T03:00:00Z | 2.5 |

## Include null values in an ad hoc stream of tables

1. Use [`array.from()`](/flux/v0/stdlib/array/from/) to create an ad hoc stream of tables.
2. Use [`debug.null()`](/flux/v0/stdlib/internal/debug/null/) to include null column values.

```js
import "array"
import "internal/debug"

array.from(
    rows: [
        {a: 1, b: 2, c: 3, d: "four"},
        {a: debug.null(type: "int"), b: 5, c: 6, d: debug.null(type: "string")}
    ]
)
```

##### The example above returns:

| a | b | c | d |
| --- | --- | --- | --- |
| 1 | 2 | 3 | four |
|  | 5 | 6 |  |

#### Related

-   [debug.null() function](/flux/v0/stdlib/internal/debug/null/)

[basic types](/flux/v0/tags/basic-types/) [data types](/flux/v0/tags/data-types/)