# NQL time\_elapsed()

The `time_elapsed()` function calculates the time elapsed since an event. The function returns the values in seconds.

Use this function with a field of *datetime* [data type](https://docs.nexthink.com/platform/understanding-key-data-platform-concepts/nexthink-query-language-nql/nql-syntax-overview/nql-data-types), for example:

* the `last_seen` field from the `devices` table
* `time` from the `device_performance.boots` table

The timeframe specified in your query does not restrict the values returned by the `time_elapsed()` function. For example, the following query retrieves only devices active in the past day, but the values returned by `time_elapsed()` may extend beyond that timeframe.

<figure><img src="https://268444917-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FxJSUDk9NTtCHYPG5EWs3%2Fuploads%2Fgit-blob-6d03d0d02d89b9fbaae72e3bedff4ab3997d0c29%2Ftime_elapsed_query_example.png?alt=media" alt=""><figcaption></figcaption></figure>

### Using with the ‘where’ clause <a href="#nqltime_elapsed-usingwiththewhereclause" id="nqltime_elapsed-usingwiththewhereclause"></a>

Use the `time_elapsed()` function in a `where` clause.

**Example:**

Retrieve the list of devices where the last operating system update was more than 15 days ago.

{% code overflow="wrap" lineNumbers="true" %}

```
devices
| where operating_system.last_update.time_elapsed() > 15d
```

{% endcode %}

### Using with the ‘list’ clause <a href="#nqltime_elapsed-usingwiththelistclause" id="nqltime_elapsed-usingwiththelistclause"></a>

Use the `time_elapsed()` function in a `list` clause.

**Example:**

List devices and the time elapsed from their last startup.

{% code overflow="wrap" lineNumbers="true" %}

```
devices
| include device_performance.boots
| where type == fast_startup
| compute last_fast_startup_time = time.last()
| list name, last_fast_startup_time.time_elapsed()
```

{% endcode %}

| Name            | Last fast startup time → time elapsed |
| --------------- | ------------------------------------- |
| device-10d267d2 | 1w 0d 1h 8min 22s 0ms                 |
| device-d1d5abc9 | 17h 38min 22s 0ms                     |
| device-5117c4c3 | 3w 1d 10h 33min 8s 0ms                |
| device-16834449 | 57min 18s 0ms                         |
| …               | …                                     |

### Using with the ‘compute’ clause <a href="#nqltime_elapsed-usingwiththecomputeclause" id="nqltime_elapsed-usingwiththecomputeclause"></a>

Use the `time_elapsed()` function in a `compute` clause.

**Example:**

List devices and the time elapsed from their last startup. Applying chaining of functions (call multiple functions on the same field).

{% code overflow="wrap" lineNumbers="true" %}

```
devices
| include device_performance.boots
| where type == fast_startup
| compute time_since_last_fast_startup = time.last().time_elapsed()
```

{% endcode %}