gbk编码：

mysql> SELECT *,
    ->  ELT(INTERVAL(CONV(HEX(left(A_UserName,1)),16,10),
    ->          0xB0A1,0xB0C5,0xB2C1,0xB4EE,0xB6EA,0xB7A2,0xB8C1,0xB9FE,0xBBF7,0
xBFA6,0xC0AC,0xC2E8,0xC4C3,0xC5B6,0xC5BE,0xC6DA,0xC8BB,0xC8F6,0xCBFA,0xCDDA,0xCE
F4,0xD1B9,0xD4D1),
    ->          'A','B','C','D','E','F','G','H','J','K','L','M','N','O','P','Q',
'R','S','T','W','X','Y','Z') as PY
    -> from o_personnel;
+------+------------+------+
| A_Id | A_UserName | PY   |
+------+------------+------+
|    1 | 首先       | S    |
|    2 | 检查       | J    |
|    3 | 我们       | W    |
|    4 | 的二       | D    |
|    5 | 进制       | J    |
|    6 | 是否       | S    |
|    7 | 适合       | S    |
|    8 | 你的       | N    |
|    9 | 平台       | P    |
+------+------------+------+
9 rows in set (0.00 sec)

mysql>

utf8编码:

SELECT filename ,
ELT(INTERVAL(CONV(HEX(left(CONVERT(filename USING gbk),1)),16,10),
0xB0A1,0xB0C5,0xB2C1,0xB4EE,0xB6EA,0xB7A2,0xB8C1,0xB9FE,0xBBF7,
0xBFA6,0xC0AC,0xC2E8,0xC4C3,0xC5B6,0xC5BE,0xC6DA,0xC8BB,0xC8F6,
0xCBFA,0xCDDA,0xCEF4,0xD1B9,0xD4D1),
'A','B','C','D','E','F','G','H','J','K','L','M','N','O','P',
'Q','R','S','T','W','X','Y','Z') as PY 
FROM youtable