> For the complete documentation index, see [llms.txt](https://php-etl.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://php-etl.gitbook.io/docs/transformers/convertcase.md).

# Convert Case

Convert string case.

```php
$etl->transform('convert_case', $options);
```

## Options

### Columns

Columns that will be transformed. If `empty`, the transformation is applied to all columns.

| Type  | Default value |
| ----- | ------------- |
| array | `[]`          |

```php
$options = ['columns' => ['name', 'email']];
```

### Mode

The mode of the conversion. It can be `lower`/`lowercase`, `upper`/`uppercase` or `title`

| Type   | Default value |
| ------ | ------------- |
| string | lower         |

```php
$options = ['mode' => 'upper'];
```

### Encoding

The character encoding.

| Type   | Default value |
| ------ | ------------- |
| string | utf-8         |

```php
$options = ['encoding' => 'ASCII'];
```