[英]Need help on Linq with group by and distinct
I am trying to perform a group by followed by a distinct to verify if a set of columns maps to only other column. 我正在尝试执行一个分组,然后由一个非重复分组来验证一组列是否仅映射到其他列。 For example, in the dataset below 例如,在下面的数据集中
Brand Product Location Customer Demand
Box A Chicago Chicago 10
Box B Chicago Milwaukee 20
Cart C Madison Milwaukee 10
Cart D Chicago Milwaukee 15
Product A, B, C are valid. 产品A,B,C有效。 But D is not valid since there exists a Product B with Chicago as Location & Milwaukee as Customer. 但是D无效,因为存在一个产品B,其中芝加哥为Location,密尔沃基为客户。 I am trying to build a LINQ query to get the exception record and having some trouble. 我试图建立一个LINQ查询来获取异常记录并遇到一些麻烦。 I am very sure I have overcomplicated my query. 我非常确定我的查询过于复杂。
var vDuplicateSupplierLitho = from p in vRecords
group p by new
{
Location = p["Location"].Cast<string>(),
Customer = p["Customer"].Cast<string>()
} into grp
select new
{
Location = grp.Key.Location,
Customer = grp.Key.Customer,
Products = from a in grp
group a by new { Product = a["Product"].Cast<string>() } into apngrp
where apngrp.Count() > 1 && apngrp.Select(a => a["Product"]).Distinct().Count() > 1
from NonUniqueRecord in apngrp
select new
{
Product = apngrp.key.Product,
Location = g.key.Location,
Customer = g.key.Customer
Demand = NonUniqueRecord["Demand"]
}
};
Thanks. 谢谢。
new[] {
new { Brand = "Box", Product = "A", Location = "Chicago", Customer = "Chicago", Demand = 10 },
new { Brand = "Box", Product = "B", Location = "Chicago", Customer = "Milwaukee", Demand = 20 },
new { Brand = "Cart", Product = "C", Location = "Madison", Customer = "Milwaukee", Demand = 10 },
new { Brand = "Cart", Product = "D", Location = "Chicago", Customer = "Milwaukee", Demand = 15 },
new { Brand = "Cart", Product = "C", Location = "Madison", Customer = "Milwaukee", Demand = 10 }
}
.GroupBy(o => new { o.Location, o.Customer })
.Where(g => g.Select(o => o.Product).Distinct().Count() > 1)
.SelectMany(g => g)
... or, in query syntax ... ...或者,在查询语法中...
from record in new[] {
new { Brand = "Box", Product = "A", Location = "Chicago", Customer = "Chicago", Demand = 10 },
new { Brand = "Box", Product = "B", Location = "Chicago", Customer = "Milwaukee", Demand = 20 },
new { Brand = "Cart", Product = "C", Location = "Madison", Customer = "Milwaukee", Demand = 10 },
new { Brand = "Cart", Product = "D", Location = "Chicago", Customer = "Milwaukee", Demand = 15 },
new { Brand = "Cart", Product = "C", Location = "Madison", Customer = "Milwaukee", Demand = 10 }
}
group record by new { record.Location, record.Customer } into grouping
where (from o in grouping select o.Product).Distinct().Count() > 1
from duplicate in grouping
select duplicate
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