mysql> show warnings;
+---------+------+------------------------------------------------------------------------+
| Level | Code | Message        |
+---------+------+------------------------------------------------------------------------+
| Warning | 1366 | Incorrect string value: '\xE3f767\x12...' for column 'passwd' at row 1 |
+---------+------+------------------------------------------------------------------------+
1 row in set (0.00 sec)

-- 将'hello world'加密，密钥为'key'，加密后的串存在@pass中
mysql> SET @pass=AES_ENCRYPT('hello world', 'key'); 
Query OK, 0 rows affected (0.00 sec)

-- 看一下加密后串的长度（都为2的整数次方）
mysql> SELECT CHAR_LENGTH(@pass);
+--------------------+
| CHAR_LENGTH(@pass) |
+--------------------+
| 16   |
+--------------------+
1 row in set (0.00 sec)

-- 使用AES_DECRYPT()解密
mysql> SELECT AES_DECRYPT(@pass, 'key');
+---------------------------+
| AES_DECRYPT(@pass, 'key') |
+---------------------------+
| hello world  |
+---------------------------+
1 row in set (0.00 sec)

mysql> CREATE TABLE t_passwd (pass1 varbinary(16), pass2 binary(16), pass3 blob);
Query OK, 0 rows affected (0.00 sec)

mysql> INSERT INTO t_passwd VALUES (AES_ENCRYPT('明文1', 'key'), AES_ENCRYPT('text2', 'key'), AES_ENCRYPT('明文_text3', 'key')); 
Query OK, 1 row affected (0.01 sec)

mysql> SELECT AES_DECRYPT(pass1, 'key'), AES_DECRYPT(pass2, 'key'), AES_DECRYPT(pass3, 'key') FROM t_passwd;
+---------------------------+---------------------------+---------------------------+
| AES_DECRYPT(pass1, 'key') | AES_DECRYPT(pass2, 'key') | AES_DECRYPT(pass3, 'key') |
+---------------------------+---------------------------+---------------------------+
| 明文1   | text2   | 明文_text3   |
+---------------------------+---------------------------+---------------------------+
1 row in set (0.00 sec)

mysql> CREATE TABLE t_passwd_2(pass1 char(32));
Query OK, 0 rows affected (0.01 sec)

mysql> INSERT INTO t_passwd_2 VALUES (HEX(AES_ENCRYPT('hello world', 'key2')));
Query OK, 1 row affected (0.00 sec)

mysql> SELECT AES_DECRYPT(UNHEX(pass1), 'key2') FROM t_passwd_2; 
+-----------------------------------+
| AES_DECRYPT(UNHEX(pass1), 'key2') |
+-----------------------------------+
| hello world   |
+-----------------------------------+
1 row in set (0.00 sec)

mysql> CREATE TABLE t_passwd_3(pass varchar(32)) CHARSET latin1;
Query OK, 0 rows affected (0.00 sec)

mysql> INSERT INTO t_passwd_3 SELECT AES_ENCRYPT('text', 'key3');
Query OK, 1 row affected (0.00 sec)
Records: 1 Duplicates: 0 Warnings: 0

mysql> SELECT AES_DECRYPT(pass, 'key3') FROM t_passwd_3;
+---------------------------+
| AES_DECRYPT(pass, 'key3') |
+---------------------------+
| text   |
+---------------------------+
1 row in set (0.00 sec)