vb.net 在数据表中查找并获取行索引
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Find and get row index in datatable
提问by hagant
DataTable.Select problem
DataTable.Select 问题
i have simple datatable like this
我有这样的简单数据表
| 1 | 2 | 3 |
|------|------|------|
| 1966 | 6544 | 1967 |
| 9560 | 3339 | 4968 |
| 0 | 9400 | 1765 |
| 0 | 5479 | 6701 |
for example i want to check if 1966 is already exist in column "1" and if it exist get row index i do code like this
例如，我想检查 1966 列是否已经存在于“1”列中，如果存在则获取行索引我执行这样的代码
Dim search() As DataRow = table.Select(" '" & i & "' = '" & value & "' ")
'where i is a integer from 1 to 3 and value is a biginteger
If search.Count > 0 Then
'get row index
Else
Console.WriteLine("not found")
End If
采纳答案by N0Alias
Unless the row index is contained in the values of the rows themselves you'll have to abandon the Select method and use a cursor based approach. This example will stop looping if a match is found:
除非行索引包含在行本身的值中，否则您将不得不放弃 Select 方法并使用基于游标的方法。如果找到匹配项，此示例将停止循环：
Dim intTargetIndex As Integer = -1
Dim intCursor As Integer = 0
Do Until intCursor = table.Rows.Count OrElse intTargetIndex > -1
If table.Rows(intCursor)(0).ToString() = value.ToString() Then
intTargetIndex = intCursor
End If
intCursor += 1
Loop
回答by ??ssa P?ngj?rdenlarp
Using your existing loop, just find the row in the table:
使用您现有的循环，只需找到表中的行：
Dim ndx As Int32
Dim rows = dtSample.Select("Id = 42")
If rows.Count > 0 Then
ndx = dtSample.Rows.IndexOf(rows(0))
End If
Return ndx
Using extension methods, you can condense it:
使用扩展方法，你可以浓缩它：
Dim ndx = dtSample.AsEnumerable().
Where(Function(q) q.Field(Of Int32)("Id") = 42).
Select(Function(z) dtSample.Rows.IndexOf(z)).
ToArray()
ndxwill be an array in this case, and will be empty when there is no match.
ndx在这种情况下将是一个数组，当没有匹配时将是空的。
回答by soohoonigan
Your query is currently trying to query number fields as strings, so if the datatable columns you're querying are indeed integers, then the correct syntax would be:
您的查询当前正在尝试将数字字段作为字符串进行查询，因此如果您查询的数据表列确实是整数，那么正确的语法将是：
Dim search() As DataRow = table.Select(i.ToString & " = " & value.ToString)
Column names and numbers don't have single quotes around them. Then, to get the index, you will need to search the table for the index of the row you returned. DataRowCollections have a way to do that, you just need to iterate through the query's return:
列名和数字周围没有单引号。然后，要获取索引，您需要在表中搜索您返回的行的索引。DataRowCollections 有一种方法可以做到这一点，您只需要遍历查询的返回：
For Each dr As DataRow In table.Select(i.ToString & " = " & value.ToString)
MsgBox(dr.Table.Rows.IndexOf(dr).ToString)
Next dr
回答by DIPIN K
Here is the code:
这是代码：
Dim rowIndex = dt.AsEnumerable().[Select](Function(r) r.Field(Of String)("Column_Name")).ToList().FindIndex(Function(col) col = "Find_Key")
