> For the complete documentation index, see [llms.txt](https://mariadb.com/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mariadb.com/docs/server/reference/sql-functions/string-functions/unhex.md).

# UNHEX

## Syntax

```bnf
UNHEX(str)
```

## Description

Performs the inverse operation of [HEX](/docs/server/reference/sql-functions/string-functions/hex.md)(str). That is, it interprets each pair of hexadecimal digits in the argument as a number and converts it to the character represented by the number. The resulting\
characters are returned as a binary string.

If `str` is `NULL`, `UNHEX()` returns `NULL`.

## Examples

```sql
SELECT HEX('MariaDB');
+----------------+
| HEX('MariaDB') |
+----------------+
| 4D617269614442 |
+----------------+

SELECT UNHEX('4D617269614442');
+-------------------------+
| UNHEX('4D617269614442') |
+-------------------------+
| MariaDB                 |
+-------------------------+

SELECT 0x4D617269614442;
+------------------+
| 0x4D617269614442 |
+------------------+
| MariaDB          |
+------------------+

SELECT UNHEX(HEX('string'));
+----------------------+
| UNHEX(HEX('string')) |
+----------------------+
| string               |
+----------------------+

SELECT HEX(UNHEX('1267'));
+--------------------+
| HEX(UNHEX('1267')) |
+--------------------+
| 1267               |
+--------------------+
```

## See Also

* [Hexadecimal literals](/docs/server/reference/sql-structure/sql-language-structure/hexadecimal-literals.md)
* [HEX()](/docs/server/reference/sql-functions/string-functions/hex.md)
* [CONV()](/docs/server/reference/sql-functions/numeric-functions/conv.md)

<sub>*This page is licensed: GPLv2, originally from*</sub> [<sub>*fill\_help\_tables.sql*</sub>](https://github.com/MariaDB/server/blob/main/scripts/fill_help_tables.sql)

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