如何在Linq中获得SUM? [英] how to get a SUM in Linq?

问题描述

我需要执行以下操作，我有一个List，其类包含2个整数id和count

I need to do the following, I have a List with a class which contains 2 integer id and count

现在我要执行以下linq查询:

Now I want to do the following linq query:

get the sum of the count for each id

，但是可能会有具有相同ID的商品，因此应将其夏季化，例如:

but there can be items with the same id, so it should be summerized e.g.:

id=1, count=12
id=2, count=1
id=1, count=2

可能是:

id=1 -> sum 14
id=2 -> sum 1

该怎么做?

推荐答案

组按Id键，然后按总和每个组中Count个:

Group the items by Id and then sum the Counts in each group:

var result = items.GroupBy(x => x.Id)
                  .Select(g => new { Id = g.Key, Sum = g.Sum(x => x.Count) });

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