C# 如何基于从树视图中选择的子节点从数据库加载datagridview？

如何基于从树视图中选择的子节点从数据库加载datagridview？例如，如果选择了制造商名称（制造商名称是子节点），则加载该制造商的所有产品

String strConn = "Server = .\\SQLEXPRESS;Database = Northwind;Integrated 
Security = SSPI;";
SqlConnection conn = new SqlConnection(strConn);
SqlDataAdapter da = new SqlDataAdapter("Select * from Suppliers", conn);
SqlDataAdapter daCategories = new SqlDataAdapter("Select * from 
Categories", conn);

da.Fill(ds, "Suppliers");
daCategories.Fill(ds, "Categories");

ds.Relations.Add("Cat_Supply", 
ds.Tables["Categories"].Columns["CategoryID"], 
ds.Tables["Suppliers"].Columns["CategoryID"]);

foreach(DataRow dr in ds.Tables["Categories"].Rows)
{
   TreeNode tn = new TreeNode(dr["CategoryName"].ToString());
   foreach (DataRow drChild in dr.GetChildRows("Cat_Supply"))
   {
          tn.Nodes.Add(drChild["CompanyNamde"].ToString());
   }
   treeView1.Nodes.Add(tn);
}

---

定义一个sperate sub来加载

DataGridView

，参数为e，即您拥有的category名称或CategoryID（更好的是，您可以将其作为标记存储在

treeveiwiitem

）

C#：

VB.NET：

Private Sub LoadCategoryTest(CategoryID As Int32)
    Dim cmdText As String = "SELECT ProductID, ProductName, CompanyName, Details, PurchasingCode FROM Products WHERE CategoryID = " & CategoryID & "; "
    Dim ds As DataSet
    Dim dt As DataTable
    ds = DatabaseAccess.GetQueryResults(cmdText)
    If ds.Tables.Count > 0 Then
        dt = ds.Tables(0)
        Me.dgBends.DataSource = dt
    End If
End Sub

Private Sub TreeView1_NodeMouseClick(sender As Object, e As TreeNodeMouseClickEventArgs) Handles TreeView1.NodeMouseClick
    Dim n As TreeNode = CType(sender, TreeNode)
    Call LoadDetail(n.Tag)  ' provided, you saved CategoryID into treenode tag
End Sub

显然，在SQL查询中输入您想要的内容。 注意：我没有解释所使用的数据库功能，我认为这超出了这个问题的范围。要使用it，只需使用树状视图事件，如

NodeMouseClick

（或

AfterSelect

等，具体取决于您的目标）：

C#

VB.NET：

Private Sub LoadCategoryTest(CategoryID As Int32)
    Dim cmdText As String = "SELECT ProductID, ProductName, CompanyName, Details, PurchasingCode FROM Products WHERE CategoryID = " & CategoryID & "; "
    Dim ds As DataSet
    Dim dt As DataTable
    ds = DatabaseAccess.GetQueryResults(cmdText)
    If ds.Tables.Count > 0 Then
        dt = ds.Tables(0)
        Me.dgBends.DataSource = dt
    End If
End Sub

Private Sub TreeView1_NodeMouseClick(sender As Object, e As TreeNodeMouseClickEventArgs) Handles TreeView1.NodeMouseClick
    Dim n As TreeNode = CType(sender, TreeNode)
    Call LoadDetail(n.Tag)  ' provided, you saved CategoryID into treenode tag
End Sub

您可以对CategoryName字符串执行相同的操作

注意：这个基本示例不包括参数化查询或绑定之类的内容。不过，它是功能性的