Mysql UNHEX() function

Mysql UNHEX() function

MySQL UNHEX() function performs the opposite operation of HEX(). This function interprets each pair of hexadecimal digits (in the argument) as a number and converts it to a character.

Syntax:

UNHEX (str)

The return value is a binary string.

MySQL Version: 5.6

Argument

Name	Description
str	A string which is to be converted to a decimal number.

Example: MySQL UNHEX() function

mysql> SELECT UNHEX('4d7953514c205475746f7269616c2c77337265736f757263');
+-----------------------------------------------------------+
| UNHEX('4d7953514c205475746f7269616c2c77337265736f757263') |
+-----------------------------------------------------------+
| MySQL Tutorial,w3resourc                                  |
+-----------------------------------------------------------+
1 row in set (0.01 sec)

mysql> SELECT UNHEX(HEX('w3resource'));
+--------------------------+
| UNHEX(HEX('w3resource')) |
+--------------------------+
| w3resource               |
+--------------------------+
1 row in set (0.00 sec)

mysql> SELECT HEX(UNHEX(1234));
+------------------+
| HEX(UNHEX(1234)) |
+------------------+
| 1234             |
+------------------+
1 row in set (0.00 sec)

In UNHEX() function the characters in the argument string must be legal hexadecimal digits i.e. '0'..'9', 'A'.. 'F', 'a'..'f'. If there are nonhexadecimal digits in argument part, the function will return NULL. See the following statement:

mysql> SELECT UNHEX('www');
+--------------+
| UNHEX('www') |
+--------------+
| NULL         |
+--------------+
1 row in set (0.00 sec)