一个sql查询语句
数据内容如下

CHECKDATE RESULTBFLAGCHECKTIME

2007-6-1186.212007-9-3 15:24:54
2007-6-1186.212007-9-3 15:25:08
2007-6-1186.212007-9-3 15:28:07
2007-6-1196.212007-9-3 15:32:14
2007-6-2173.212007-9-3 15:25:08
2007-6-2173.212007-9-3 15:28:07
2007-6-2193.212007-9-3 15:32:14
2007-6-3178.312007-9-3 15:25:08
2007-6-3178.312007-9-3 15:28:07
2007-6-3213.312007-9-3 15:32:14
要获得每天当中的第一个数据和最后一个数据.上面是按checktime排序的数据
得到内容如下.
2007-6-1186.212007-9-3 15:24:54
2007-6-1196.212007-9-3 15:32:14
2007-6-2173.212007-9-3 15:25:08
2007-6-2193.212007-9-3 15:32:14
2007-6-3178.312007-9-3 15:25:08
2007-6-3213.312007-9-3 15:32:14

[解决办法]
Select * from 表 t where not exists
(Select * from 表 where CHECKDATE=t.CHECKDATE
and CHECKTIME <t.CHECKTIME)
Union all
Select * from 表 t where not exists
(Select * from 表 where CHECKDATE=t.CHECKDATE
and CHECKTIME> t.CHECKTIME)