sql union排序问题，为什么会这样

Question

mysql数据库

(select syncTime From t_bzRecord_1601 order by syncTime desc) union (select syncTime From t_bzRecord_1512 order by syncTime desc);

查询结果：
+---------------------+
| syncTime |
+---------------------+
| 2016-01-01 10:27:36 |
| 2016-01-26 14:01:51 |
| 2015-12-23 10:27:36 |
| 2015-12-23 10:27:48 |
| 2015-12-23 10:28:00 |
| 2015-12-23 10:28:12 |
| 2015-12-23 10:28:24 |
| 2015-12-23 10:28:36 |
| 2015-12-23 10:28:48 |
| 2015-12-23 10:29:00 |
| 2015-12-23 10:29:12 |
| 2015-12-23 10:29:24 |
| 2015-12-23 10:29:37 |
| 2015-12-23 10:29:48 |
| 2015-12-23 10:30:00 |
| 2015-12-23 10:30:12 |
| 2015-12-23 10:30:24 |

单独查，两个结果都是降序。
union后，结果就变为升序了。
这不科学啊

Answer 1

把排序提到最外面试试select * from(你的sql) order by xxx