sql中去除重复的项
用slq语句实现除去字段T中重复的项：
ID T
1 1-2
2 2-3
3 3-4
4 1-2
5 2-3
所要结果：
ID T
1 1-2
2 2-3
3 3-4
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用slq语句实现除去字段T中重复的项：
ID T
1 1-2
2 2-3
3 3-4
4 1-2
5 2-3
所要结果：
ID T
1 1-2
2 2-3
3 3-4
===================================================
select a.id,a.t from Table_1 as a inner join(select id=min(id) from Table_1 group by t) as b on a.id=b.id
select * from Table_1 where ID in (select id=min(id) from Table_1 group by t)
两个sql都可以，关键是select id=min(id) from Table_1 group by t