MySQL自定義排序函式FIELD()
MySQL可以通過field()函式自定義排序，格式：field(value,str1,str2,str3,str4)，value與str1、str2、str3、str4比較，返回1、2、3、4，如遇到null或者不在列表中的資料則返回0. 這個函式好像Oracle中沒有專門提供（也可能是我沒有用到），不過自己實現這樣一個函式還是比較簡單的。
mysql> select * from driver_log order by name;
+--------+-------+------------+-------+
| rec_id | name| trav_date| miles |
+--------+-------+------------+-------+
|1 | Ben| 2006-08-30 |152 |
|9 | Ben| 2006-09-02 |79 |
|5 | Ben| 2006-08-29 |131 |
|8 | Henry | 2006-09-01 |197 |
|6 | Henry | 2006-08-26 |115 |
|4 | Henry | 2006-08-27 |96 |
|3 | Henry | 2006-08-29 |300 |
|10 | Henry | 2006-08-30 |203 |
|7 | Suzi| 2006-09-02 |502 |
|2 | Suzi| 2006-08-29 |391 |
+--------+-------+------------+-------+
10 rows in set (0.00 sec)
mysql> select * from driver_log order by field(name,'Suzi','Ben','Henry');
+--------+-------+------------+-------+
| rec_id | name| trav_date| miles |
+--------+-------+------------+-------+
|2 | Suzi| 2006-08-29 |391 |
|7 | Suzi| 2006-09-02 |502 |
|1 | Ben| 2006-08-30 |152 |
|9 | Ben| 2006-09-02 |79 |
|5 | Ben| 2006-08-29 |131 |
|8 | Henry | 2006-09-01 |197 |
|6 | Henry | 2006-08-26 |115 |
|4 | Henry | 2006-08-27 |96 |
|3 | Henry | 2006-08-29 |300 |
|10 | Henry | 2006-08-30 |203 |
+--------+-------+------------+-------+
10 rows in set (0.00 sec)
mysql> select * from driver_log order by field(name,'Suzi','Ben');
+--------+-------+------------+-------+
| rec_id | name| trav_date| miles |
+--------+-------+------------+-------+
|10 | Henry | 2006-08-30 |203 |
|8 | Henry | 2006-09-01 |197 |
|6 | Henry | 2006-08-26 |115 |
|4 | Henry | 2006-08-27 |96 |
|3 | Henry | 2006-08-29 |300 |
|7 | Suzi| 2006-09-02 |502 |
|2 | Suzi| 2006-08-29 |391 |
|5 | Ben| 2006-08-29 |131 |
|9 | Ben| 2006-09-02 |79 |
|1 | Ben| 2006-08-30 |152 |
+--------+-------+------------+-------+
10 rows in set (0.00 sec)
mysql> select * from driver_log order by field(name,'Suzi','Ben') desc;
+--------+-------+------------+-------+
| rec_id | name| trav_date| miles |
+--------+-------+------------+-------+
|1 | Ben| 2006-08-30 |152 |
|9 | Ben| 2006-09-02 |79 |
|5 | Ben| 2006-08-29 |131 |
|2 | Suzi| 2006-08-29 |391 |
|7 | Suzi| 2006-09-02 |502 |
|8 | Henry | 2006-09-01 |197 |
| 6 | Henry | 2006-08-26 |115 |
|4 | Henry | 2006-08-27 |96 |
|3 | Henry | 2006-08-29 |300 |
|10 | Henry | 2006-08-30 |203 |
+--------+-------+------------+-------+
10 rows in set (0.00 sec)