UNCOMPRESS(string_to_uncompress) uncompresses a string compressed by the COMPRESS() function. : UNCOMPRESS « Encryption Compression Functions « MySQL Tutorial

1. MySQL Tutorial
2. Encryption Compression Functions
3. UNCOMPRESS

mysql>
mysql> SELECT UNCOMPRESS(COMPRESS('any string'));
+------------------------------------+
| UNCOMPRESS(COMPRESS('any string')) |
+------------------------------------+
| any string                         |
+------------------------------------+
1 row in set (0.00 sec)

mysql>
mysql> SELECT UNCOMPRESS('any string');
+--------------------------+
| UNCOMPRESS('any string') |
+--------------------------+
| NULL                     |
+--------------------------+
1 row in set, 1 warning (0.00 sec)

mysql>