转：mysql 根据英文首字母来查询汉字函数.txt

mysql> SELECT *,
    ->  CHAR(INTERVAL(CONV(HEX(left(A_UserName,1)),16,10),
    ->          0xB0A1,0xB0C5,0xB2C1,0xB4EE,0xB6EA,0xB7A2,0xB8C1,0xB9FE,
    ->          0xBBF7,0xBBF7,0xBFA6,0xC0AC,0xC2E8,0xC4C3,0xC5B6,0xC5BE,
    ->          0xC6DA,0xC8BB,0xC8F6,0xCBFA,0xCDDA,0xCDDA,0xCDDA,0xCEF4,
    ->          0xD1B9,0xD4D1)+64) 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)

---------------

INTERVAL(N,N1,N2,N3,...)

Returns 0 if N < N1, 1 if N < N2 and so on or -1 if N is NULL. All arguments are treated as integers. It is required that N1 < N2 < N3 < ... < Nn for this function to work correctly. This is because a binary search is used (very fast).

mysql> SELECT INTERVAL(23, 1, 15, 17, 30, 44, 200);

-> 3

mysql> SELECT INTERVAL(10, 1, 10, 100, 1000);

-> 2

mysql> SELECT INTERVAL(22, 23, 30, 44, 200);

-> 0