c#winfrom treeview递归问题

Question

我遇到了一个问题，需要将一张表里的数据，弄成treeview形式，
sql 文件是这个

https://www.wenwenlove.cn/my/script.sql ,我放到我服务器上了

这个表里目前有4级结构，分别是1，2，3，4，后面可能有5，或则。。。
能帮我解决的万分感谢

Answer 1

TreeNode tn1 = treeView1.Nodes.Add("", "存货分类");
DataTable dt =DBHelpr.Query("select clnvCCode,clnvCName,ilnvCGrade,blnvCend from InventoryClass");

       // cometree(tn1.Nodes, dt, "",1);

        DataTable dts = GetNewDataTable(dt, "ilnvCGrade=" + 1, "clnvCName asc");
        for (int i = 0; i < dts.Rows.Count; i++)
        {
            tn1.Nodes.Add(dts.Rows[i]["clnvCName"].ToString(), dts.Rows[i]["clnvCName"].ToString());
            if (dts.Rows[i]["blnvCend"].ToString()=="0")
            cometree(tn1.Nodes[i].Nodes, dt, dts.Rows[i]["clnvCCode"].ToString(), 2);
        }

                     public void cometree(TreeNodeCollection tn, DataTable dt, string zkey, int ilnvCGrade)
    {
        DataTable dts = GetNewDataTable(dt, "clnvCCode like'" + zkey + "%' and ilnvCGrade=" + ilnvCGrade, "clnvCName asc");
        for (int i = 0; i < dts.Rows.Count; i++)
        {
            tn.Add(dts.Rows[i]["clnvCName"].ToString(), dts.Rows[i]["clnvCName"].ToString());
            if (dts.Rows[i]["blnvCend"].ToString() == "0")
            cometree(tn[i].Nodes, dt, dts.Rows[i]["clnvCCode"].ToString(), ilnvCGrade+1);
        }
    }

    /// 执行DataTable中的查询返回新的DataTable
    /// </summary>
    /// <param name="dt">源数据DataTable</param>
    /// <param name="condition">查询条件</param>
    /// <returns></returns>
    private DataTable GetNewDataTable(DataTable dt, string condition, string sortstr)
    {
        DataTable newdt = new DataTable();

        newdt = dt.Clone();
        DataRow[] dr = dt.Select(condition, sortstr);
        for (int i = 0; i < dr.Length && i < 200; i++)
        {
            newdt.ImportRow((DataRow)dr[i]);
        }

        return newdt;//返回的查询结果
    }