---
{
    "title": "unhex",
    "language": "zh-CN"
}
---

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# unhex
## description
### Syntax

`VARCHAR unhex(VARCHAR str)`

输入字符串，如果字符串长度为0或者为奇数，返回空串；
如果字符串中包含`[0-9]、[a-z]、[A-Z]`之外的字符，返回空串；
其他情况每两个字符为一组转化为16进制后的字符，然后拼接成字符串输出


## example

```
mysql> select unhex('@');
+------------+
| unhex('@') |
+------------+
|            |
+------------+

mysql> select unhex('41');
+-------------+
| unhex('41') |
+-------------+
| A           |
+-------------+

mysql> select unhex('4142');
+---------------+
| unhex('4142') |
+---------------+
| AB            |
+---------------+
```
## keyword
UNHEX