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方法一：group by (取最小的id)select min(id) id，T from Table_1 group by T方法二：union （不需要id）select T from Table_1 where 1=0unionselect T from Table_1
方法三：DISTINCT
select DISTINCT T from Table_1
sql中去除重复的项
原文地址：http://www.cnblogs.com/eyye/p/5090692.html
