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

# toupper

> This page explains how to use the toupper function in APL.

The `toupper` function converts all characters in a string to uppercase. Use this function to normalize text for case-insensitive operations, standardize identifiers, or format strings for emphasis in output.

## For users of other query languages

If you come from other query languages, this section explains how to adjust your existing queries to achieve the same results in APL.

<AccordionGroup>
  <Accordion title="Splunk SPL users">
    In Splunk SPL, you use the `upper` function. APL's `toupper` provides the same functionality.

    <CodeGroup>
      ```sql Splunk example theme={null}
      | eval uppercase=upper(field)
      ```

      ```kusto APL equivalent theme={null}
      ['sample-http-logs']
      | extend uppercase = toupper(field)
      ```
    </CodeGroup>
  </Accordion>

  <Accordion title="ANSI SQL users">
    In ANSI SQL, you use `UPPER` for uppercase conversion. APL's `toupper` provides the same functionality.

    <CodeGroup>
      ```sql SQL example theme={null}
      SELECT UPPER(field) AS uppercase FROM logs;
      ```

      ```kusto APL equivalent theme={null}
      ['sample-http-logs']
      | extend uppercase = toupper(field)
      ```
    </CodeGroup>
  </Accordion>
</AccordionGroup>

## Usage

### Syntax

```kusto theme={null}
toupper(value)
```

### Parameters

| Name  | Type   | Required | Description                               |
| ----- | ------ | -------- | ----------------------------------------- |
| value | string | Yes      | The input string to convert to uppercase. |

### Returns

Returns the input string with all characters converted to uppercase.

## Use case examples

<Tabs>
  <Tab title="Log analysis">
    Standardize HTTP status codes and methods for consistent alerting and reporting.

    **Query**

    ```kusto theme={null}
    ['sample-http-logs']
    | extend normalized_method = toupper(method)
    | extend alert_status = iff(status startswith '5', toupper(strcat('ERROR_', status)), status)
    | summarize request_count = count() by normalized_method, alert_status
    | sort by request_count desc
    | limit 10
    ```

    [Run in Playground](https://play.axiom.co/axiom-play-qf1k/query?initForm=%7B%22apl%22%3A%22%5B%27sample-http-logs%27%5D%20%7C%20extend%20normalized_method%20%3D%20toupper\(method\)%20%7C%20extend%20alert_status%20%3D%20iff\(status%20startswith%20%275%27%2C%20toupper\(strcat\(%27ERROR_%27%2C%20status\)\)%2C%20status\)%20%7C%20summarize%20request_count%20%3D%20count\(\)%20by%20normalized_method%2C%20alert_status%20%7C%20sort%20by%20request_count%20desc%20%7C%20limit%2010%22%7D)

    **Output**

    | normalized\_method | alert\_status | request\_count |
    | ------------------ | ------------- | -------------- |
    | GET                | 200           | 5432           |
    | POST               | 201           | 2341           |
    | GET                | ERROR\_500    | 234            |

    This query normalizes HTTP methods to uppercase and creates emphasized error status codes for critical alerts.
  </Tab>

  <Tab title="OpenTelemetry traces">
    Create uppercase service identifiers for system monitoring and alerting.

    **Query**

    ```kusto theme={null}
    ['otel-demo-traces']
    | extend service_code = toupper(substring(['service.name'], 0, 3))
    | summarize span_count = count(), avg_duration = avg(duration) by service_code
    | sort by span_count desc
    | limit 10
    ```

    [Run in Playground](https://play.axiom.co/axiom-play-qf1k/query?initForm=%7B%22apl%22%3A%22%5B%27otel-demo-traces%27%5D%20%7C%20extend%20service_code%20%3D%20toupper\(substring\(%5B%27service.name%27%5D%2C%200%2C%203\)\)%20%7C%20summarize%20span_count%20%3D%20count\(\)%2C%20avg_duration%20%3D%20avg\(duration\)%20by%20service_code%20%7C%20sort%20by%20span_count%20desc%20%7C%20limit%2010%22%7D)

    **Output**

    | service\_code | span\_count | avg\_duration |
    | ------------- | ----------- | ------------- |
    | FRO           | 4532        | 125ms         |
    | CHE           | 3421        | 234ms         |
    | CAR           | 2987        | 89ms          |

    This query creates three-letter uppercase service codes for compact monitoring displays and alerts.
  </Tab>
</Tabs>

## List of related functions

* [tolower](/apl/scalar-functions/string-functions/tolower): Converts strings to lowercase. Use this for the opposite transformation.
* [totitle](/apl/scalar-functions/string-functions/totitle): Converts strings to title case. Use this for capitalized formatting.
* [strcmp](/apl/scalar-functions/string-functions/strcmp): Compares strings. Use toupper before strcmp for case-insensitive comparisons.
* [strcat](/apl/scalar-functions/string-functions/strcat): Concatenates strings. Use this with toupper to build emphasized messages.