MySQL Tutorial/Encryption Compression Functions/DES DECRYPT
DES_DECRYPT(crypt_str[,key_str]) (Decrypts a string encrypted with DES_ENCRYPT().)
mysql>
mysql> select DES_DECRYPT(DES_ENCRYPT("credit_card_number"));
+------------------------------------------------+
| DES_DECRYPT(DES_ENCRYPT("credit_card_number")) |
+------------------------------------------------+
| credit_card_number |
+------------------------------------------------+
1 row in set (0.00 sec)
mysql>