vb.net 对数据表进行分组和求和查询
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Group by and sum query on datatable
提问by ruedi
I have a strongly typed DataTablethat looks as follows:
我有一个强类型DataTable，如下所示：
|Team|FirstName|LastName|Hours
|A|Henry|Manny|3
|A|Henry|Manny|5
|A|Johny|Tenny|2
|A|Johny|Tenny|3
|B|Frank|Tank|4
|B|Frank|Tank|5
What I am trying to achieve is to sum the Hours by First and Lastname so my result table should look like:
我想要实现的是按名字和姓氏对小时数求和，因此我的结果表应如下所示：
|Team|FirstName|LastName|Hours
|A|Henry|Manny|8
|A|Johny|Tenny|5
|B|Frank|Tank|9
I tried so many thinks. One of it was:
我尝试了很多想法。其中之一是：
dim query = From row In _dataset.Table1.AsEnumerable
Group by row.FirstName, row.LastName Into MAGroup = Group
Select New with { . First = row.FirstName, .Last = row.LastName, .Sum = sum(MAGroup.Hours)}
But always as soon as I start with the first anonymous member in the Select statement I don't get intellisense help and everything is underlined. I really would be so thankful if anyone could help me with the query.
但是总是只要我从 Select 语句中的第一个匿名成员开始，我就不会得到智能帮助，并且所有内容都带有下划线。如果有人可以帮助我进行查询，我真的会非常感激。
回答by Tim Schmelter
So you want to group by FirstName+LastName? Then group by an anonymous type:
所以你想按FirstName+分组LastName？然后按匿名类型分组：
Dim query = From row In _dataset.Table1.AsEnumerable()
Group row By Name = New With {
Key .FirstName = row.FirstName,
Key .LastName = row.LastName
} Into NameGroup = Group
Select New With {
.First = Name.FirstName,
.Last = Name.LastName,
.Sum = NameGroup.Sum(Function(r) r.Hours)
}
