vb.net 多维列表 - vb
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multi dimensional list - vb
提问by user1562652
I have a problem that can't solve...
我有一个无法解决的问题...
I have the set of data, which i want to add in two dimensional list (in Visual Basic)
我有一组数据，我想将其添加到二维列表中（在 Visual Basic 中）
the result of sql query is:
sql查询的结果是：
ID value1 value2
0001 a 10
0001 b 10
0002 a 30
0002 b 20
0002 c 15
0003 a 5
....
....
so, i want add all elements into two dimensional list:
所以，我想将所有元素添加到二维列表中：
Dim multilist As New List(Of List(Of String))
multilist.Add(New List(Of String))
multilist.Add(New List(Of String))
multilist.Add(New List(Of String))
and I need a vb code that will add elemenets with different ID's to different lists of one two dimensional list
我需要一个 vb 代码，它将具有不同 ID 的元素添加到一个二维列表的不同列表中
thank you :)
谢谢你 ：）
result must be:
结果必须是：
in first list elements 1 and 2
in the second list elements 3,4,5
in the third list the last element
回答by Tim Schmelter
You should use a DataTableinstead, then you just have to use a DataAdapterto fill it and Linq-To-DataSetto get your ID-Groups and List(Of DataTable):
您应该使用 aDataTable代替，然后您只需要使用 aDataAdapter来填充它并Linq-To-DataSet获取您的 ID-Groups 和List(Of DataTable)：
Dim table = New DataTable()
Using con = New SqlClient.SqlConnection("Connection-String")
Using da = New SqlDataAdapter("SQL-Query", con)
da.Fill(table)
End Using
End Using
Dim idGroups = From row In table
Let id = row.Field(Of String)("ID")
Group row By id Into Group
Dim idTables As List(Of DataTable) = idGroups.
Select(Function(x) x.Group.CopyToDataTable()).
ToList()
Since you are using .NET 2 LINQ is not an option. Here is an approach using a Dictionaryinstead of a Listwhere the key is the ID and the value is the DataTable:
由于您使用的是 .NET 2 LINQ 不是一个选项。这是一种使用 aDictionary而不是 a的方法，List其中键是 ID，值是DataTable：
Dim idTables As New Dictionary(Of String, DataTable)
For Each row As DataRow In table.Rows
Dim id As String = DirectCast(row("ID"), String)
Dim dt As DataTable = Nothing
If Not idTables.TryGetValue(id, dt) Then
dt = table.Clone() ' empty table with same schema '
idTables.Add(id, dt)
End If
dt.ImportRow(row)
Next
This does not require the resultset to be ordered by the ID.
这不需要按 ID 对结果集进行排序。
