encryption and decryption in mysql

In mysql we can encrypt and decrypt the data in many ways.
some of the examples are as follows:

1.) Encode and decode in mysql

mysql> select ENCODE('guessme', 'kiran');
+----------------------------+
| ENCODE('guessme', 'kiran') |
+----------------------------+
| ÕD]10÷8                      |
+----------------------------+
1 row in set (0.00 sec)

mysql> select decode('ÕD]10÷8','kiran');
+---------------------------+
| decode('ÕD]10÷8','kiran')   |
+---------------------------+
| guessme                   |
+---------------------------+
1 row in set (0.00 sec)

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2.) AES_ENCRYPT and DES_ENCRYPT
mysql> create table app (user varchar(100),password varchar(100));
Query OK, 0 rows affected (0.09 sec)

mysql> insert into app values('user,',AES_ENCRYPT('text1','samplekey'));
Query OK, 1 row affected (0.01 sec)

mysql> select * from app;
+-------+-------------------------+
| user  | password                |
+-------+-------------------------+
| user, | QWâÃâºÂ¿1{3_pþyk        |
+-------+-------------------------+
1 row in set (0.00 sec)

mysql> select user, AES_DECRYPT(password,'samplekey') from app;

+-------+-----------------------------------+
| user  | AES_DECRYPT(password,'samplekey') |
+-------+-----------------------------------+
| user, | text1                             |
+-------+-----------------------------------+
1 row in set (0.00 sec)