我有两个强类型数据表(dt1
):
|FirstName|LastName|Val1|Val2|
|Tony |Stark |34 |35 |
|Steve |Rogers |12 |23 |
|Natasha |Romanoff|2 |100 |
和第二个(dt2
)
|FirstName|LastName|Val1|Val2|
|Tony |Stark |16 |5 |
|Bruce |Banner |2 |1 |
|Steve |Rogers |54 |40 |
我尝试创建一个新的数据表,在其中添加人员的值。我需要一个外部联接,因为我需要所有人并且第二个表中的值减半。
所以结果应该是这样的:
|FirstName|LastName|Val1|Val2|
|Tony |Stark |42 |37.5|
|Steve |Rogers |39 |43 |
|Natasha |Romanoff|2 |100 |
|Bruce |Banner |1 |0.5 |
我的方法是使用 LINQ:
Dim query =
from a in ds1.Table1
Join b in ds2.Table2
On a.FirstName + a.LastName Equals b.FirstName + b.Lastname
Select New With {
.FirstName = a.FirstName,
.LastName = a.LastName,
.Val1 = a.Val1 + b.Val1 *0.5,
.Val2 = a.Val2 + b.Val2 *0.5
}
但我并没有让所有人都接受这种方法。我也试过了
Dim query =
From a in ds1.Table1
From b in ds2.Table2
Select New With{
Key .KeyName = a.FirstName + a.LastName = b.FirstName + b.FirstName,
.Val1 = a.Val1 + b.Val1 *0.5,
.Val2 = a.Val2 + b.Val2 * 0.5
}
现在我得到了每个人的许多条目。谁能帮我完成这件事。我不知道在没有 Linq 的情况下是否有另一种方法可以解决这个问题。
最佳答案
一个使用 group by
的例子。需要考虑的是,在执行 group by
和 Sum
操作之前,第二个表中的所有值都必须除以 2。我在 .Concat
var dt1 = new List<MyClass>();
dt1.Add(new MyClass { FirstName = "Tony", LastName = "Stark", Val1 = 34, Val2 = 35});
dt1.Add(new MyClass { FirstName = "Steve", LastName = "Rogers", Val1 = 12, Val2 = 23});
dt1.Add(new MyClass { FirstName = "Natasha", LastName = "Romanoff", Val1 = 2, Val2 = 100 });
var dt2 = new List<MyClass>();
dt2.Add(new MyClass { FirstName = "Tony", LastName = "Stark", Val1 = 16, Val2 = 5 });
dt2.Add(new MyClass { FirstName = "Bruce", LastName = "Banner", Val1 = 2, Val2 = 1 });
dt2.Add(new MyClass { FirstName = "Steve", LastName = "Rogers", Val1 = 54, Val2 = 40 });
var q = from a in dt1
.Concat(
from b in dt2
select new MyClass
{
FirstName = b.FirstName,
LastName = b.LastName,
Val1 = b.Val1 * 0.5m,
Val2 = b.Val2 * 0.5m
})
group a by new {a.FirstName, a.LastName}
into g
select new
{
g.First().FirstName,
g.First().LastName,
Val1 = g.Sum(x => x.Val1),
Val2 = g.Sum(x => x.Val2),
};
foreach (var s in q)
{
Console.WriteLine("{0} {1} {2} {3}", s.FirstName,s.LastName,s.Val1,s.Val2);
}
结果
Tony Stark 42,0 37,5
Steve Rogers 39,0 43,0
Natasha Romanoff 2 100
Bruce Banner 1,0 0,5
关于c# - 将两个数据表中的值添加到一个新数据表中,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/25552274/