Question

假设我有下表：

user type amount
2    a    10
2    b    20
2    c    40
3    a    15
3    b    20
3    c    45

我想用（c - （a + b））用户和类型替换（c）金额，我该怎么做？感谢

Answer 1

这是一种方式：

更新（现在使用Sum）：

from item in table
group item by item.user into g
let a = (from i in g where i.type == "a" select i.amount).Sum()
let b = (from i in g where i.type == "b" select i.amount).Sum()
let c = (from i in g where i.type == "c" select i.amount).Sum()
select c - (a + b);

Answer 2

我建议对 Steven 的答案进行扩展，因为这只会返回一系列标量c值，而不是让它们与用户或{{1}相关联}和a金额。试试这个：

然后，如果您想将其转换回表格形式：

var query1 = from i in table
             group i by i.user
             into g
             let a = g.Where(t => t.type == "a").Sum(t => t.amount)
             let b = g.Where(t => t.type == "b").Sum(t => t.amount)
             let c = g.Where(t => t.type == "c").Sum(t => t.amount)
                   - (a + b)
             select new {user = g.Key, a, b, c};

注意：我已经测试了这个并且它有效。

在LINQ中分组，总和

2 个答案: