Question

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），请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);
}

Answer 1

定义一个spearate子来加载DataGridView，并使用一个参数（如您所愿）将类别名称或CategoryID（最好将其存储为TreeVeiwItem中的标签））。

C＃：

private void LoadCategoryTest(Int32 CategoryID)
{
    string cmdText = "SELECT ProductID, ProductName, CompanyName, Details, PurchasingCode FROM Products WHERE CategoryID = " + CategoryID + "; ";
    DataSet ds;
    DataTable dt;
    ds = DatabaseAccess.GetQueryResults(cmdText);
    if (ds.Tables.Count > 0)
    {
        dt = ds.Tables(0);
        this.dgBends.DataSource = dt;
    }
}

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

很显然，将想要获取的任何内容都放入SQL查询中。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。要使用它，请仅使用树视图事件，例如NodeMouseClick（或AfterSelect等，这取决于您要实现的目标）：

C＃

private void TreeView1_NodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
{
    TreeNode n = (TreeNode)sender;
    LoadDetail(n.Tag);  // provided, you saved CategoryID into treenode tag
}

VB.NET：

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：此基本示例不包括参数查询或绑定之类的内容。不过，它是有功能的。

如何基于从树视图中选择的子节点从数据库加载datagridview？

1 个答案: