SQL取最新数据

测试数据
SELECT  DATETIME,CODE,TAXUP FROM ANT where CODE='MZE01002200' order by DATETIME desc
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         DATETIME          CODE            TAXUP 
2011-05-10 15:46:50.217 MZE01002200 0.00000000
2011-04-18 11:18:32.063 MZE01002200 86.35000000
2010-12-31 17:09:19.277 MZE01002200 0.00000000
2010-12-31 17:09:19.277 MZE01002200 71.99000000
2010-12-27 14:34:25.030 MZE01002200 75.29000000
2010-12-27 13:52:09.233 MZE01002200 73.30000000
2010-11-26 11:29:06.860 MZE01002200 74.27000000
2010-09-07 08:41:58.920 MZE01002200 66.65000000
2010-09-06 11:17:39.780 MZE01002200 66.65000000
2010-09-06 11:17:39.780 MZE01002200 66.65000000
2010-09-02 19:13:25.953 MZE01002200 66.65000000
2010-09-02 19:13:25.953 MZE01002200 66.65000000
2010-08-16 14:34:14.110 MZE01002200 63.21000000
2010-08-03 17:30:47.437 MZE01002200 63.21000000
2010-06-07 16:41:53.017 MZE01002200 64.32000000
2010-05-17 14:38:12.077 MZE01002200 70.10000000
2010-05-17 13:57:08.627 MZE01002200 70.10000000
2010-05-10 10:18:21.610 MZE01002200 70.00000000
2010-05-08 10:19:12.297 MZE01002200 70.10000000
2010-03-04 14:12:34.907 MZE01002200 68.80000000
2009-11-07 10:36:39.733 MZE01002200 0.00000000
2009-09-09 11:07:24.813 MZE01002200 0.00000000
2009-07-16 15:09:49.937 MZE01002200 0.00000000
2009-07-13 10:56:19.610 MZE01002200 0.00000000需要得到的是
2011-04-18 11:18:32.063 MZE01002200 86.35000000
判断是取CODE最新时间的TAXUP,如果TAXUP没有就取下一条数据TAXUP.