> ## Documentation Index
> Fetch the complete documentation index at: https://docs.anlytic.com/llms.txt
> Use this file to discover all available pages before exploring further.

# IsNull

Returns True if the argument contains missing data values, and False if the argument is not Null. Often applied to a column of data to test for Null values.

**Category:** `logical`

**Syntax:**

```
IsNull(argument)
```

**Returns:** `BooleanColumn`

**Context Filtering:** ✓ Yes

## Parameters

| Name       | Type          | Required | Description                                                                    |
| ---------- | ------------- | -------- | ------------------------------------------------------------------------------ |
| `argument` | `column\|any` | ✓ Yes    | Any argument can be provided. The function can analyze one argument at a time. |

## Validation

* Minimum parameters: 1
* Maximum parameters: 1

## Examples

```
IsNull([Sales])
```

Returns False for rows where sales data exists and True for rows where there is no data.

```
IsNull([prm-date-range].start) and IsNull([prm-date-range].end)
```

Returns True when no start and end date is provided in a Date Range parameter.