Question

我有一个DataGridView，有2列。第一列填充了文件夹路径，第二列为空。每个文件夹路径中都有一个名为DB1的数据库。我想从每个数据库中提取1个值（VALUE），然后将该值放在第二列的相应数据库路径旁边。这是我正在使用的查询

Select CODE, VALUE from DB1 where CODE = 2419

我知道如何填充DataGridView以及如何从数据库中提取1个值，但是我不知道从哪里开始。

修改

我设法创建了工作循环，但不知道如何将这些值添加到datagridview中的相应位置。

 For Each row As DataGridViewRow In DataGridView1.Rows
        Dim sendtroopid As String
        sendtroopid = row.Cells("CODE").Value
        On Error Resume Next
        Dim FilePath As String = sendtroopid 'DATABASE PATH
        Using con As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & FilePath & _
        " ;Extended Properties=dBASE IV")
            con.Open()
            Using cmd As New OleDbCommand("SELECT CODE, VALUE FROM DB1 WHERE CODE = @CODE", con)
                cmd.Parameters.AddWithValue("@CODE", "2419")
                Using reader As OleDbDataReader = cmd.ExecuteReader()
                    While (reader.Read())
                        MsgBox(reader("VALUE"))
                    End While
                End Using
            End Using
        End Using
    Next

编辑2

使用上面的代码，我获得了msgbox中的所有值。剩下的就是插入另一个循环来将所有这些值（从第0行开始）放到datagridview中。如果我用

替换msgbox

For i As Integer = 0 To DataGridView1.Rows.Count - 1
DataGridView1.Rows(i).Cells(1).Value = (reader("VALUE"))
Next

然后所有行都只填充最后一个值（来自最后一个数据库的值）。

编辑3 我已经改变了

value = reader.Read()

带

While (reader.Read())
value = reader("VALUE")
End While

Answer 1

我仍然不确定您的查询是如何工作的，但假设确实如此，我已经更改了您的代码。

For Each row As DataGridViewRow In DataGridView1.Rows
    Dim sendtroopid As String
    sendtroopid = row.Cells("CODE").Value
    On Error Resume Next
    Dim FilePath As String = sendtroopid 'DATABASE PATH
    Dim value as string = "" ' declare a string variable to hold the result
    Using con As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & FilePath & _
    " ;Extended Properties=dBASE IV")
        con.Open()
        Using cmd As New OleDbCommand("SELECT CODE, VALUE FROM DB1 WHERE CODE = @CODE", con)
            cmd.Parameters.AddWithValue("@CODE", "2419")
            Using reader As OleDbDataReader = cmd.ExecuteReader()
                value = reader.Read()
            End Using
        End Using
    End Using
    row.Cells(1) = value ' put it in the datagridview cell
Next

Answer 2

在行绘制时填写..

Protected Sub GridView1_RowDataBound(sender As Object, e As _
     System.Web.UI.WebControls.GridViewRowEventArgs) Handles _
      GridView1.RowDataBound

   Dim DGRow As GridViewRow = sender
   If DGRow.RowType = DataControlRowType.DataRow Then
      Dim TestPath As String = DGRow.Cells(0).Text
      Dim FoundKey As String = GetKeyFromOtherDatabase(TestPath)
      DGRow.Cells(1).Text = FoundKey 
   End If

End Sub

Private Function GetKeyFromOtherDatabase(testpath) As String
    Dim FoundKey As String = "" 
    '   FoundKey = Double something magical...  
    Return FoundKey
End Function

循环访问数据库获取值并将其放在datagridview中的特定位置

2 个答案: