KDB选择其他查询结果中的x [英] KDB select where x in other query result

问题描述

我有一个查询

top:flip select [10] Name from `Val xdesc select sum Val by Name from table

我想根据该结果进行另一个查询过滤

and I want another query filtering based on that result

select from table where Name in top

但是这给了我一个类型错误.我也尝试过

however that gives me a type error. I also tried

select from table where {x in y}[Name; top]

但是会产生一个空表.有什么建议可以做到吗?

but that yields an empty table. Any suggestions how this can be done?

推荐答案

in的第二个参数必须是列表类型，因此您可以这样做:

The second parameter to in needs to be of list type, so you could do:

select from table where Name in exec Name from top

或:

select from table where Name in top[`Name]

您还可以将top列为开始列表.使用 take 运算符可获取排序表中的前10个项目:

You could also make top a list to begin with. Using the take operator to get the first 10 items in the sorted table:

top:10#(exec Name from `Val xdesc select sum Val by Name from table)

然后您就可以做到:

select from table where Name in top

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