从Excel文件中只有1列添加到我的MySQLDB中

Question

我正在尝试将数据从Excel文件插入到Mysql DB中。它的工作原理但问题是，它只插入一列。我需要插入Excel文件中的所有列

这是我的代码

protected void add_Click(object sender, EventArgs e)
{

    if (importfile.HasFile)
    {
        string path = string.Concat((Server.MapPath("~/temp/" + importfile.FileName)));
        importfile.PostedFile.SaveAs(path);
        OleDbConnection oleConn = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + path + ";Extended Properties=Excel 8.0;");
        OleDbCommand oleCmd = new OleDbCommand("SELECT * FROM [Sheet1$]", oleConn);
        OleDbDataAdapter oleAdapter = new OleDbDataAdapter(oleCmd);
        DataSet ds = new DataSet();
        oleAdapter.Fill(ds);
        DataTable Dt = new DataTable();
        Dt = ds.Tables[0];
        string userId = (string)(Session["id"]);
        string groupName = groupname.Text.ToString();
        try {
            for (int i = 0; i < Dt.Rows.Count; i++)
            {
                DataRow row = Dt.Rows[i];
                int columnCount = Dt.Columns.Count;
                string[] columns = new string[columnCount];
                for (int j = 0; j < columnCount; j++)
                {
                    columns[j] = row[j].ToString();
                }
                conn.Open();
                string sql = "INSERT INTO contacts(user_id, idNum, contact_name, contact_number, group_name)";
                sql += "VALUES('" + userId + "','" + columns[0] + "','" + columns[1] + "','" + columns[2] + "','" + groupName + "')";
                MySqlCommand cmd = new MySqlCommand(sql, conn);
                int x = cmd.ExecuteNonQuery();
                if (x > 0)
                {
                    string message = "Success!";
                    System.Text.StringBuilder sb = new System.Text.StringBuilder();
                    sb.Append("<script type = 'text/javascript'>");
                    sb.Append("window.onload = function(){");
                    sb.Append("alert('");
                    sb.Append(message);
                    sb.Append("')};");
                    sb.Append("</script>");

                    ClientScript.RegisterStartupScript(this.GetType(), "alert", sb.ToString());
                    Response.Redirect("viewgroups.aspx");
                    conn.Close();
                }
            }
        }
        catch (Exception)
        {
                string message = "Failed!";
                System.Text.StringBuilder sb = new System.Text.StringBuilder();
                sb.Append("<script type = 'text/javascript'>");
                sb.Append("window.onload = function(){");
                sb.Append("alert('");
                sb.Append(message);
                sb.Append("')};");
                sb.Append("</script>");

                ClientScript.RegisterStartupScript(this.GetType(), "alert", sb.ToString());

        }

这很难过。请帮忙。感谢