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问题描述
标准SQL聚合函数max()将返回组中的最大值; min()将返回最低值.
The standard SQL aggregate function max() will return the highest value in a group; min() will return the lowest.
Oracle中是否有聚合函数来从组中返回随机值?还是一些技巧来实现这一目标?
Is there an aggregate function in Oracle to return a random value from a group? Or some technique to achieve this?
例如,给定表foo:
group_id value 1 1 1 5 1 9 2 2 2 4 2 8SQL查询
select group_id, max(value), min(value), some_aggregate_random_func(value) from foo group by group_id;可能产生:
group_id max(value), min(value), some_aggregate_random_func(value) 1 9 1 1 2 8 2 4显然,最后一列是该组中的任何随机值.
with, obviously, the last column being any random value in that group.
推荐答案您可以尝试以下操作
select deptno,max(sal),min(sal),max(rand_sal) from( select deptno,sal,first_value(sal) over(partition by deptno order by dbms_random.value) rand_sal from emp) group by deptno /我们的想法是按照随机顺序对组中的值进行排序,然后选择第一个.我可以想到其他方法,但是效率不高.
The idea is to sort the values within group in random order and pick the first.I can think of other ways but none so efficient.
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Oracle聚合函数返回组的随机值?
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