如何從不同的窗體中獲取DataGridView.SelectedRows（）。Cells（）的值？

Question

我有2種形式，並且在兩種形式的每一種中有DataGridView（chatform和）。

在chatform中，我創建了一個DataGridView，其中每行都生成了Button。

每個Button點擊時會加載一個形式，並且當形式我想在始發chatform的SelectedRow.Cell從DataGridView值。

碼（chatform）：

Public Sub loadtoDGV() 
    Dim sqlq As String = "SELECT * FROM chattbl" 
    Dim sqlcmd As New SqlCommand 
    Dim sqladpt As New SqlDataAdapter 
    Dim tbl As New DataTable 

    With sqlcmd 
     .CommandText = sqlq 
     .Connection = conn 
    End With 

    With sqladpt 
     .SelectCommand = sqlcmd 
     .Fill(tbl) 
    End With 

    DataGridView1.Rows.Clear() 
    For i = 0 To tbl.Rows.Count - 1 
     With DataGridView1 
      .Rows.Add(tbl.Rows(i)("Username"), tbl.Rows(i)("Title"), tbl.Rows(i)("ChatDateTime")) 
     End With 
    Next 
    conn.Close() 
End Sub 

Private Sub ChatForm_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load 
    loadtoDGV() 
End Sub 

碼（DataGridView1.CellContentClick）：

Private Sub grdData_CellContentClick(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DataGridView1.CellContentClick 
    Dim colName As String = DataGridView1.Columns(e.ColumnIndex).Name 
    If colName = "Detail" Then 
     Prodetail.Show() 
     MessageBox.Show(String.Format("You clicked the button in row {0} of the Detail column", e.RowIndex)) 
    End If 
End Sub 

碼（）：

Public Sub loadtoDGV2() 

    Dim i As Integer 
    i = ChatForm.DataGridView1.SelectedRows.Count 
    MsgBox(i) 

    Dim compareai As String = ChatForm.DataGridView1.SelectedRows(i).Cells(1).Value 
    Dim sqlq As String = "SELECT * FROM Chattbl WHERE Title =" & compareai & "" 
    Dim sqlcmd As New SqlCommand 
    Dim sqladpt As New SqlDataAdapter 
    Dim tbl As New DataTable 

    With sqlcmd 
     .CommandText = sqlq 
     .Connection = conn 
    End With 

    With sqladpt 
     .SelectCommand = sqlcmd 
     .Fill(tbl) 
    End With 

    DataGridView1.Rows.Clear() 
    For i = 0 To tbl.Rows.Count - 1 
     With DataGridView1 
      .Rows.Add(tbl.Rows(i)("Username"), tbl.Rows(i)("Title"), tbl.Rows(i)("ChatDateTime"), tbl.Rows(i)("ChatContent")) 
     End With 
    Next 
    conn.Close() 
End Sub 

Private Sub Prodetail_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load 
    loadtoDGV2() 
End Sub 

我做了什麼錯？

我試圖使用MsgBox(i) i = SelectedRow(0)假設它會顯示第一行的數據，但DataGridView1在不會從數據庫中加載任何數據。

我沒有觀察到任何錯誤，我只是沒有解決方案。

Answer 1

第一個問題是您正在調用該類而不是實例。 VB.NET將允許你調用表單的一個實例作爲它的名字，但它在每次使用時都是同一個實例。我不會建議這樣做。

首先我要改變這一點：

Private Sub grdData_CellContentClick(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DataGridView1.CellContentClick 
    Dim colName As String = DataGridView1.Columns(e.ColumnIndex).Name 
    If colName = "Detail" Then 
     Prodetail.Show() 
     MessageBox.Show(String.Format("You clicked the button in row {0} of the Detail column", e.RowIndex)) 
    End If 
End Sub 

要這樣：

Private Sub grdData_CellContentClick(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DataGridView1.CellContentClick 
    Dim colName As String = DataGridView1.Columns(e.ColumnIndex).Name 
    If colName = "Detail" Then 
     Dim newDetailForm as new Proddetail(dataGridView1.Rows(e.RowIndex).Cells(1).Value) 
     newDetailForm.show() 
     MessageBox.Show(String.Format("You clicked the button in row {0} of the Detail column", e.RowIndex)) 
    End If 
End Sub 

然後在Proddetail類，你需要添加一個構造函數和成員如下：

Private SearchValue as String 

Public Sub New(byval theSearchValue as string) 
    InitalizeComponent() 

    SearchValue = theSearchValue 
End Sub 

然後在你的加載程序中：

Public Sub loadtoDGV2()  
    Dim sqlq As String = "SELECT * FROM Chattbl WHERE Title =" & SearchValue & "" 
    Dim sqlcmd As New SqlCommand 
    Dim sqladpt As New SqlDataAdapter 
    Dim tbl As New DataTable 

    With sqlcmd 
     .CommandText = sqlq 
     .Connection = conn 
    End With 

    With sqladpt 
     .SelectCommand = sqlcmd 
     .Fill(tbl) 
    End With 

    DataGridView1.Rows.Clear() 
    For i = 0 To tbl.Rows.Count - 1 
     With DataGridView1 
      .Rows.Add(tbl.Rows(i)("Username"), tbl.Rows(i)("Title"), tbl.Rows(i)("ChatDateTime"), tbl.Rows(i)("ChatContent")) 
     End With 
    Next 
    conn.Close() 
End Sub 

然後，這應該在Proddetail類的新實例中顯示單擊行的詳細信息。

我添加了一個自定義的參數化構造函數到接受SQL查詢字符串值的類。通過這種方式，當您在代碼中創建表單的新實例時，您始終可以傳入搜索字符串，這會導致您要查看的詳細信息。