> ## Documentation Index
> Fetch the complete documentation index at: https://docs.e6data.com/llms.txt
> Use this file to discover all available pages before exploring further.

# ISNULL

> Tests whether a value is SQL NULL.

<div className="e6-meta"><span className="e6-eyebrow e6-eyebrow--quiet">Scalar function</span></div>

Returns TRUE for NULL and FALSE for non-NULL input; the result itself is not NULL.

## Syntax

### Scalar

```sql theme={"theme":{"light":"github-light","dark":"github-dark"}}
isnull(value)
```

## Arguments

| Name | Type | Required | Description |
| - | - | - | - |
| value | BOOLEAN, TINYINT, SMALLINT, INTEGER, BIGINT, FLOAT, DOUBLE, DECIMAL(p, s), STRING, BINARY, DATE, TIME, TIMESTAMP, ARRAY, MAP or STRUCT | Yes | Value whose NULL status is tested. For DECIMAL(p, s), p is precision (total digits) and s is scale (digits after the decimal point). |

## Returns

* Type: BOOLEAN
* Possible values: TRUE or FALSE.
* NULL behavior: Returns TRUE for NULL and FALSE for non-NULL input; the result itself is not NULL.

## Properties

| Property | Value |
| - | - |
| Deterministic | Yes |
| Supports window usage | No |
| Exact result | Yes |

## Usage notes

* This is a one-argument Boolean test, not the two-argument replacement function named ISNULL in some other engines.
* INTEGER and INT mean the same type; STRING means VARCHAR text. NULL can be used with a supported type. Cast NULL explicitly when its type would otherwise be unclear.
* Deterministic: The same inputs and settings produce the same result.

## Examples

### Typical behavior

```sql theme={"theme":{"light":"github-light","dark":"github-dark"}}
SELECT isnull(CAST(NULL AS INT)) AS null_value, isnull(1) AS present;
```

| null\_value | present |
| - | - |
| true | false |

### An empty string is not NULL

```sql theme={"theme":{"light":"github-light","dark":"github-dark"}}
SELECT isnull('') AS empty_string, isnull(CAST(NULL AS VARCHAR)) AS null_string;
```

| empty\_string | null\_string |
| - | - |
| false | true |

## Related functions

* [nvl](/query/sql/functions/conditional/nvl)


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