数据查询的问题
如果一个数据表里有五个字段，多条数据前3个字段相同，只取一条最新的，请问怎么取？？

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eg: tb(a, b, c, d, e)

select * from tb as t
where not exists(select 1 from tb where a = t.a and b = t.b and c = t.c and d < t.d)
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楼上的好想写错了,如果d是时间字段

eg: tb(a, b, c, d, e)

select * from tb as t
where not exists(select 1 from tb where a = t.a and b = t.b and c = t.c and d > t.d)