> ## Documentation Index
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<AgentInstructions>

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  "path": "/reference-sql/functions-reference/string/upper",
  "feedback": "Description of the issue"
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> Reference material for UPPER function

# UPPER

Converts the input string to uppercase characters. Note that Firebolt uses the `POSIX` locale, therefore `upper` only converts the ASCII characters “a” through “z” to uppercase. Non-ASCII characters remain unchanged.

## Syntax

```sql theme={"theme":{"light":"github-light","dark":"github-dark"}}
UPPER(<expression>)
```

## Parameters

| Parameter      | Description                                         | Supported input types |
| :------------- | :-------------------------------------------------- | :-------------------- |
| `<expression>` | The string to be converted to uppercase characters. | `TEXT`                |

## Return Type

`TEXT`

## Example

The following example converts a game player's username from lowercase to uppercase characters:

```sql theme={"theme":{"light":"github-light","dark":"github-dark"}}
SELECT
	UPPER('esimpson') as username
```

**Returns**: `ESIMPSON`

Because Firebolt uses the `POSIX` locale, non-ASCII characters are not uppercased:

```sql theme={"theme":{"light":"github-light","dark":"github-dark"}}
SELECT UPPER('München')
```

**Returns**: `MüNCHEN`