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？？
[解决办法]
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)
[解决办法]
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)
