1、mysql in 排序 按in里面的顺序来排序
select * from table where id IN (3,6,9,1,2,5,8,7);这样的情况取出来后，其实，id还是按1,2,3,4,5,6,7,8,9,排序的，但如果我们真要按IN里面的顺序排序怎么办？SQL能不能完成？是否需要取回来后再foreach一下？
其实可以这样
select * from table where id IN (3,6,9,1,2,5,8,7) order by field(id,3,6,9,1,2,5,8,7);出来的顺序就是指定的顺序了
关于这种排序的效率， 有文章指出： FIELD(str,str1,str2,str3,…) Returns the index (position) of str in the str1, str2, str3, … list. Returns 0 if str is not found. 排序过程：把选出的记录的 id 在 FIELD 列表中进行查找，并返回位置，以位置作为排序依据。 这样的用法，会导致 Using filesort，是效率很低的排序方式。除非数据变化频率很低，或者有长时间的缓存，否则不建议用这样的方式排序。 作者建议在程序代码中自行排序。 但是也有人说这种排序不会出现什么性能瓶颈 具体还是自己测试一下吧。2、其他实例：
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 | | 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 | +--------+-------+------------+-------+ 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 | | 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 | +--------+-------+------------+-------+ 10 rows in set (0.00 sec)