方法一：

复制代码 代码如下:
public void creattree(int fid, TreeNode parentnode)
{

DataTable dt = new DataTable();
dt = op.BindGroup();
DataRow[] drs = dt.Select("parentid=" + fid);
foreach (DataRow row in drs)
{
if (parentnode != null)
{
TreeNode tempnode = new TreeNode();
tempnode.Text = row["groupname"].ToString();
tempnode.Name = row["groupid"].ToString();
parentnode.Nodes.Add(tempnode);
creattree(Convert.ToInt32(row["groupid"]), tempnode);
}
else
{
TreeNode tempnode = new TreeNode();
tempnode.Text = row["groupname"].ToString();
tempnode.Name = row["groupid"].ToString();
treeView1.Nodes.Add(tempnode);
creattree(Convert.ToInt32(row["groupid"]), tempnode);
}
}
}

private void bindtree()
{
treeView1.Nodes.Clear();
creattree(0,(TreeNode)null);
}

方法二：

复制代码 代码如下:
public void AddTree(int ParentID, TreeNode pNode)
{
DataTable dt = new DataTable();
dt = op.BindGroup();
DataView dvTree = new DataView(dt);
//过滤ParentID,得到当前的所有子节点
dvTree.RowFilter = "parentid = " + ParentID;

foreach (DataRowView Row in dvTree)
{
TreeNode Node = new TreeNode();
if (pNode == null)
{ //添加根节点
Node.Text = Row["groupname"].ToString();
treeView1.Nodes.Add(Node);
//Node.Expanded = true;

AddTree(Int32.Parse(Row["groupid"].ToString()), Node); //再次递归
}
else
{ //添加当前节点的子节点
Node.Text = Row["groupname"].ToString();
pNode.Nodes.Add(Node);
//Node.Expanded = true;
AddTree(Int32.Parse(Row["groupid"].ToString()), Node); //再次递归
}
}
}

private void bindtree()
{
treeView1.Nodes.Clear();
AddTree(0, (TreeNode)null);
}