# UPPER

將字串轉換為大寫字母。

## 語法

```
UPPER(STRING)
```

## 引數

#### STRING

類型：`string`

字元序列。

## 傳回

類型： `string`

`STRING` 為大寫字母。

***

## 範例

> SELECT UPPER("a") = "A" AND UPPER("abc") = "ABC" AND UPPER("123") = "123" AND UPPER("abc") = "ABC" AND UPPER("-=@#$") = "-=@#$" AND UPPER(null) is null AND UPPER(CAST(null as varchar)) is null

| 字串 | 輸出 |
| --- | --- |
| a | A |
| abc | ABC |
| 123 | 123 |
| abc | ABC |
| -=@#$ | -=@#$ |
| `null` | `null` |