DES_DECRYPT(crypt_str[,key_str]) (Decrypts a string encrypted with DES_ENCRYPT().) : DES_DECRYPT « Encryption Compression Functions « MySQL Tutorial

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

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>