# Is null

> Supported in: Batch, Faster, Streaming

Returns true if the input is null, can optionally treat empty strings as null.

**Expression categories:** Boolean

## Declared arguments

* **Expression:** The expression to check for null values.<br>*Expression\<AnyType>*
* *optional* **Treat empty strings as null:** Whether to treat empty strings as null values.<br>*Literal\<Boolean>*

**Output type:** *Boolean*

## Examples

### Example 1: Base case

**Argument values:**

* **Expression:** *empty string*
* **Treat empty strings as null:** true

**Output:** true

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### Example 2: Base case

**Argument values:**

* **Expression:** hello
* **Treat empty strings as null:** *null*

**Output:** false

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### Example 3: Base case

**Argument values:**

* **Expression:** 1
* **Treat empty strings as null:** *null*

**Output:** false

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### Example 4: Base case

**Argument values:**

* **Expression:** *null*
* **Treat empty strings as null:** *null*

**Output:** true

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