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这个linq用vb.net的语法怎么写？
我有一个class(clsStudent)，里面有StudentID,Name,Age,ClassID,Gender
然后我有个 lstStudent是clsStudent的list
我现在想知道在lstStudent里面有多少学生有相同Age,ClassID,Gender;并把这些学生的Name和StudentID打印出来
我在网上看的似乎语法不对，麻烦指点下
如果我这么写不对，那如何才能写才能达到我的要求呢
谢谢
然后我有个 lstStudent是clsStudent的list
我现在想知道在lstStudent里面有多少学生有相同Age,ClassID,Gender;并把这些学生的Name和StudentID打印出来
我在网上看的似乎语法不对，麻烦指点下
- from s as clsStudent in lstStudent group s by new {s.Age, s.Gender, s.ClassID} into mygrp ...‘这样就通不过，后面不会写了
如果我这么写不对，那如何才能写才能达到我的要求呢
谢谢
...全文
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clear_zero 2012-05-30
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[Quote=引用 19 楼 的回复:]
VB.NET code
'发觉这两种方式都可以，发楼主参考：
Dim query1=From x in empList _
Group x By x.Age, x.Sex Into g=Group _
Select New With {g,g.Count()}
Dim query2……
[/Quote]
我这里第二种不成...我用的是VS2008
谢谢你
VB.NET code
'发觉这两种方式都可以，发楼主参考：
Dim query1=From x in empList _
Group x By x.Age, x.Sex Into g=Group _
Select New With {g,g.Count()}
Dim query2……
[/Quote]
我这里第二种不成...我用的是VS2008
谢谢你
q107770540 2012-05-30
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'发觉这两种方式都可以，发楼主参考：
Dim query1=From x in empList _
Group x By x.Age, x.Sex Into g=Group _
Select New With {g,g.Count()}
Dim query2=From el In empList _
Group el By Key = new with {key el.Age, key el.Sex} _
Into Group _
Select New With {.key = Key, _
.count = Group.Count()}
clear_zero 2012-05-29
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我来补充下即便是一个条件
这样还是不会出现group by 所要的结果，还是每一个都算了
Dim query= From s in lstStudent _
Group by k= New With {s.Age} into g = Group _
Select New with _
{ .StudentID=String.Join(",",g.Select(Function(x) x.StudentID).ToArray()), _
.Name=String.Join(",",g.Select(Function(x) x.Name).ToArray()), _
.Count=g.Count() _
}
这样还是不会出现group by 所要的结果，还是每一个都算了
clear_zero 2012-05-29
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论坛好了阿，我刚才发言论坛维护。我已经弄出来了
这样就是我要的结果，看来关键是new with这里；具体怎么为什么不同只能高人来讲解了。关键是new with这个编译过了
祝Tim答辩顺利
Dim query= From s in lstStudent _
Group s by s.Age，s.Gender, s.ClassID into g = Group _
Select New with _
{ .StudentID=String.Join(",",g.Select(Function(x) x.StudentID).ToArray()), _
.Name=String.Join(",",g.Select(Function(x) x.Name).ToArray()), _
.Count=g.Count() _
}
这样就是我要的结果，看来关键是new with这里；具体怎么为什么不同只能高人来讲解了。关键是new with这个编译过了
祝Tim答辩顺利
threenewbee 2012-05-29
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有意思，我手上没有环境，晚上来研究下。
q107770540 2012-05-29
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你也可随时关注这个帖子，我已经在MSDN上提出了疑问：
http://social.microsoft.com/Forums/zh-CN/adonetzhchs/thread/7f06ff9e-a704-411e-9220-7a86963a290e
http://social.microsoft.com/Forums/zh-CN/adonetzhchs/thread/7f06ff9e-a704-411e-9220-7a86963a290e
q107770540 2012-05-29
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刚做了个DEMO，同样的数据，用VB.NET 和C# 进行分组，得到的数据竟然不一样
明天论文答辩回来再研究一下，暂时未找到错在哪里 。。。
Sub Main
Dim empList As New List(Of Employee)()
empList.Add(New Employee() With _
{.ID = 1, .FName = "John", .Age = 23, .Sex = "M"c})
empList.Add(New Employee() With _
{.ID = 2, .FName = "Mary", .Age = 25, .Sex = "F"c})
empList.Add(New Employee() With _
{.ID = 3, .FName = "Amber", .Age = 23, .Sex = "M"c})
empList.Add(New Employee() With _
{.ID = 4, .FName = "Kathy", .Age = 25, .Sex = "F"c})
empList.Add(New Employee() With _
{.ID = 5, .FName = "Lena", .Age = 27, .Sex = "F"c})
empList.Add(New Employee() With _
{.ID = 6, .FName = "Bill", .Age = 28, .Sex = "M"c})
empList.Add(New Employee() With _
{.ID = 7, .FName = "Celina", .Age = 27, .Sex = "F"c})
empList.Add(New Employee() With _
{.ID = 8, .FName = "John", .Age = 28, .Sex = "M"c})
Dim query = empList.GroupBy(Function(x) New With { .Age=x.Age, .Sex= x.Sex}) _
.Select(Function(g) New With {g.Key, g.Count()})
For Each employee In query
Console.WriteLine(employee.Count)
Next employee
End Sub
Public Class Employee
Private privateID As Integer
Public Property ID() As Integer
Get
Return privateID
End Get
Set(ByVal value As Integer)
privateID = value
End Set
End Property
Private privateFName As String
Public Property FName() As String
Get
Return privateFName
End Get
Set(ByVal value As String)
privateFName = value
End Set
End Property
Private privateAge As Integer
Public Property Age() As Integer
Get
Return privateAge
End Get
Set(ByVal value As Integer)
privateAge = value
End Set
End Property
Private privateSex As Char
Public Property Sex() As Char
Get
Return privateSex
End Get
Set(ByVal value As Char)
privateSex = value
End Set
End Property
End Class
void Main()
{
var empList =new List<Employee>
{
new Employee {ID = 1, FName = "John", Age = 23, Sex = 'M'},
new Employee {ID = 2, FName = "Mary", Age = 25, Sex = 'F'},
new Employee {ID = 3, FName = "Amber", Age = 23, Sex = 'M'},
new Employee {ID = 4, FName = "Kathy", Age = 25, Sex = 'F'},
new Employee {ID = 5, FName = "Lena", Age = 27, Sex = 'F'},
new Employee {ID = 6, FName = "Bill", Age = 28, Sex = 'M'},
new Employee {ID = 7, FName = "Celina", Age = 27, Sex = 'F'},
new Employee {ID = 8, FName = "John", Age = 28, Sex = 'M'}
};
var query = empList.GroupBy(x => new { x.Age, x.Sex})
.Select(g=>new {g.Key, Count=g.Count()});
foreach (var employee in query )
Console.WriteLine(employee.Count);
}
public class Employee
{
public int ID {get;set;}
public string FName {get;set;}
public int Age {get;set;}
public char Sex {get;set;}
}
明天论文答辩回来再研究一下，暂时未找到错在哪里 。。。
q107770540 2012-05-29
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LINQ 是支持多列分组的 这个毋庸置疑
clear_zero 2012-05-29
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上面有一个错误
dim lstStudent as new list(of clsStudent)
for i as integer =0 to 3
dim tempS as new clsStudent
with tempS
.Age=15
.Gender="M"
.ClassID=1
.StudentID=i
.Name="Test_" & i
end with
lstStudent.add (tempS)
next
clear_zero 2012-05-29
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好的
就是这么一个测试数据
dim lstStudent as new list(of clsStudent)
for i as integer =0 to 3
dim tempS as new clsStudent
with tempS
.Age=15
.Gender=M
.ClassID=1
.StudentID=i
.Name="Test_" & i
end with
lstStudent.add (tempS)
next
就是这么一个测试数据
threenewbee 2012-05-29
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贴一些测试数据上来。
clear_zero 2012-05-29
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[Quote=引用 8 楼 的回复:]
Dim query= From s in lstStudent _
Group s by New With {s.Age, s.Gender, s.ClassID} into g = Group _
Select New with _
{ _
.Age=g.Key.Age , _
……
[/Quote]
谢谢你的帮助我这样语法虽然写过了
Dim query= From s in lstStudent _
Group by k= New With {s.Age, s.Gender, s.ClassID} into g = Group _
Select New with _
{ _
.Age=k.Age , _
.Gender=k.Gender, _
.ClassID=k.ClassID, _
.StudentID=String.Join(",",g.Select(Function(x) x.StudentID).ToArray()), _
.Name=String.Join(",",g.Select(Function(x) x.Name).ToArray()), _
.Count=g.Count() _
}
结果没有起到group by 的作用；原来多少还是多少。每一个count都是1
但是我准备的数据里面有重复的，可惜没有去掉
但是如果我只选择其中一个属性作为group by的标准就会成功
Dim query= From s in lstStudent _
Group s by s.Age into g = Group _
Select New with _
{ .StudentID=String.Join(",",g.Select(Function(x) x.StudentID).ToArray()), _
.Name=String.Join(",",g.Select(Function(x) x.Name).ToArray()), _
.Count=g.Count() _
}
难道说linq不支持多列作为goup by 的条件呢？我尝试了两个Age,Gender都不可以。不知道是不是可以冒昧的请你作个实验。看看是不是本来就不支持还是哪里需要改进？
谢谢
Dim query= From s in lstStudent _
Group s by New With {s.Age, s.Gender, s.ClassID} into g = Group _
Select New with _
{ _
.Age=g.Key.Age , _
……
[/Quote]
谢谢你的帮助我这样语法虽然写过了
Dim query= From s in lstStudent _
Group by k= New With {s.Age, s.Gender, s.ClassID} into g = Group _
Select New with _
{ _
.Age=k.Age , _
.Gender=k.Gender, _
.ClassID=k.ClassID, _
.StudentID=String.Join(",",g.Select(Function(x) x.StudentID).ToArray()), _
.Name=String.Join(",",g.Select(Function(x) x.Name).ToArray()), _
.Count=g.Count() _
}
结果没有起到group by 的作用；原来多少还是多少。每一个count都是1
但是我准备的数据里面有重复的，可惜没有去掉
但是如果我只选择其中一个属性作为group by的标准就会成功
Dim query= From s in lstStudent _
Group s by s.Age into g = Group _
Select New with _
{ .StudentID=String.Join(",",g.Select(Function(x) x.StudentID).ToArray()), _
.Name=String.Join(",",g.Select(Function(x) x.Name).ToArray()), _
.Count=g.Count() _
}
难道说linq不支持多列作为goup by 的条件呢？我尝试了两个Age,Gender都不可以。不知道是不是可以冒昧的请你作个实验。看看是不是本来就不支持还是哪里需要改进？
谢谢
q107770540 2012-05-29
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Dim query= From s in lstStudent _
Group s by New With {s.Age, s.Gender, s.ClassID} into g = Group _
Select New with _
{ _
.Age=g.Key.Age , _
.Gender=g.Key.Gender, _
.ClassID=g.Key.ClassID, _
.StudentID=String.Join(",",g.Select(Function(x) x.StudentID).ToArray()), _
.Name=String.Join(",",g.Select(Function(x) x.Name).ToArray()), _
.Count=g.Count() _
}
Group s by New With {s.Age, s.Gender, s.ClassID} into g = Group _
Select New with _
{ _
.Age=g.Key.Age , _
.Gender=g.Key.Gender, _
.ClassID=g.Key.ClassID, _
.StudentID=String.Join(",",g.Select(Function(x) x.StudentID).ToArray()), _
.Name=String.Join(",",g.Select(Function(x) x.Name).ToArray()), _
.Count=g.Count() _
}
q107770540 2012-05-29
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Dim query= From s in lstStudent _
Group s by New With {s.Age, s.Gender, s.ClassID} into g = Group _
Select New with _
{
.Age=g.Key.Age , _
.Gender=g.Key.Gender, _
.ClassID=g.Key.ClassID, _
.StudentID=String.Join(",",g.Select(Function(x) x.StudentID).ToArray()), _
.Name=String.Join(",",g.Select(Function(x) x.Name).ToArray()), _
.Count=g.Count() _
}
clear_zero 2012-05-29
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[Quote=引用 3 楼 的回复:]
VB.NET code
Dim query= From s in lstStudent _
Group s by New With {s.Age, s.Gender, s.ClassID} into g = Group _
Select New with
{
.Age=g.Key.Age ,
……
[/Quote]
谢谢阿
这个还是不行
问题出在
Dim query= From s in lstStudent _
Group s by New With {s.Age, s.Gender, s.ClassID} into g = Group _
Select New with
{
.Age=g.Key.Age , '--g.key这个不认
.Gender=g.Key.Gender,
.ClassID=g.Key.ClassID,
.StudentID=string.Join(",",g.Select(x=>x.StudentID).ToArray()),'假定 StudentID为string 类型
.Name=string.Join(",",g.Select(x=>x.Name).ToArray()),'假定 Name为string 类型
.Count=g.Count()
}
还有就是x也不认
另外我按照你给的连接的如下例子写了一个
Dim categories = From p In db.Products _
Group By Key = New With {p.CategoryID, p.SupplierID} Into Group _
Select Key, Group
也不行，发现虽然通过了，但是并没有起到group by 的作用。
不知道还有什么办法，谢谢
VB.NET code
Dim query= From s in lstStudent _
Group s by New With {s.Age, s.Gender, s.ClassID} into g = Group _
Select New with
{
.Age=g.Key.Age ,
……
[/Quote]
谢谢阿
这个还是不行
问题出在
Dim query= From s in lstStudent _
Group s by New With {s.Age, s.Gender, s.ClassID} into g = Group _
Select New with
{
.Age=g.Key.Age , '--g.key这个不认
.Gender=g.Key.Gender,
.ClassID=g.Key.ClassID,
.StudentID=string.Join(",",g.Select(x=>x.StudentID).ToArray()),'假定 StudentID为string 类型
.Name=string.Join(",",g.Select(x=>x.Name).ToArray()),'假定 Name为string 类型
.Count=g.Count()
}
还有就是x也不认
另外我按照你给的连接的如下例子写了一个
Dim categories = From p In db.Products _
Group By Key = New With {p.CategoryID, p.SupplierID} Into Group _
Select Key, Group
也不行，发现虽然通过了，但是并没有起到group by 的作用。
不知道还有什么办法，谢谢
q107770540 2012-05-29
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q107770540 2012-05-29
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q107770540 2012-05-29
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Dim query= From s in lstStudent _
Group s by New With {s.Age, s.Gender, s.ClassID} into g = Group _
Select New with
{
.Age=g.Key.Age ,
.Gender=g.Key.Gender,
.ClassID=g.Key.ClassID,
.StudentID=string.Join(",",g.Select(x=>x.StudentID).ToArray()),'假定 StudentID为string 类型
.Name=string.Join(",",g.Select(x=>x.Name).ToArray()),'假定 Name为string 类型
.Count=g.Count()
}clear_zero 2012-05-29
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[Quote=引用 1 楼 的回复:]
var query=from s in lstStudent
group s by new {s.Age, s.Gender, s.ClassID} into g
select new
{
Age=g.Key.Age,
Gender=g.Key.Gender,
……
[/Quote]
谢谢，这个怎么写成vb.net的语法阿？
上面的在vb.net里面通不过
dim query=from s in lstStudent
group s by new with {s.Age, s.Gender, s.ClassID} into g
select new with
{
Age=g.Key.Age,
Gender=g.Key.Gender,
ClassID=g.Key.ClassID,
StudentID=string.Join(",",g.Select(x=>x.StudentID).ToArray()),//假定 StudentID为string 类型
Name=string.Join(",",g.Select(x=>x.Name).ToArray()),//假定 Name为string 类型
Count=g.Count()
}
改成这样后，就是Anonymous type member name must be preceded by a period的错误
麻烦了
var query=from s in lstStudent
group s by new {s.Age, s.Gender, s.ClassID} into g
select new
{
Age=g.Key.Age,
Gender=g.Key.Gender,
……
[/Quote]
谢谢，这个怎么写成vb.net的语法阿？
上面的在vb.net里面通不过
dim query=from s in lstStudent
group s by new with {s.Age, s.Gender, s.ClassID} into g
select new with
{
Age=g.Key.Age,
Gender=g.Key.Gender,
ClassID=g.Key.ClassID,
StudentID=string.Join(",",g.Select(x=>x.StudentID).ToArray()),//假定 StudentID为string 类型
Name=string.Join(",",g.Select(x=>x.Name).ToArray()),//假定 Name为string 类型
Count=g.Count()
}
改成这样后，就是Anonymous type member name must be preceded by a period的错误
麻烦了
q107770540 2012-05-29
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var query=from s in lstStudent
group s by new {s.Age, s.Gender, s.ClassID} into g
select new
{
Age=g.Key.Age,
Gender=g.Key.Gender,
ClassID=g.Key.ClassID,
StudentID=string.Join(",",g.Select(x=>x.StudentID).ToArray()),//假定 StudentID为string 类型
Name=string.Join(",",g.Select(x=>x.Name).ToArray()),//假定 Name为string 类型
Count=g.Count()
};
group s by new {s.Age, s.Gender, s.ClassID} into g
select new
{
Age=g.Key.Age,
Gender=g.Key.Gender,
ClassID=g.Key.ClassID,
StudentID=string.Join(",",g.Select(x=>x.StudentID).ToArray()),//假定 StudentID为string 类型
Name=string.Join(",",g.Select(x=>x.Name).ToArray()),//假定 Name为string 类型
Count=g.Count()
};
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