Syntax:
ENCODE(str,pass_str)

Encrypt str using pass_str as the password. The result is a binary
string of the same length as str. To decrypt the result, use DECODE().

The ENCODE() function should no longer be used. If you still need to
use ENCODE(), a salt value must be used with it to reduce risk. For
example:

ENCODE('plaintext', CONCAT('my_random_salt','my_secret_password'))

A new random salt value must be used whenever a password is updated.

URL: http://dev.mysql.com/doc/refman/5.1/en/encryption-functions.html

