C#开发WinForm清空DataGridView控件绑定的数据

this.dgvDemo.DataSource = null

this.dgvDemo.Rows.Clear()

DataTable dt = this.dgvDemo.DataSource as DataTable;
dt.Rows.Clear();
this.dgvDemo.DataSource = dt;

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Configuration;
using System.Data;
using System.Data.sqlClient;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.windows.FORMs;
 
namespace DataGridViewDemo
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
 
        string strCon = ConfigurationManager.ConnectionStrings["DbConnection"].ConnectionString;
 
        private void btn_BindingData_Click(object sender, EventArgs e)
        {
            DataTable dt = GetDataSource();
            this.dgvDemo.DataSource = dt;
        }
 
        private DataTable GetDataSource()
        {
            DataTable dt = new DataTable();
            SqlConnection conn = new SqlConnection(strCon);
            string strSQL = "SELECT XIANGMUCDDM AS '项目代码',XIANGMUMC AS '项目名称', DANJIA AS '单价',SHULIANG AS '数量' FROM InPatientBillDt WHERE 就诊ID='225600'";
            SqlCommand cmd = new SqlCommand(strSQL, conn);
            SqlDataAdapter adapter = new SqlDataAdapter();
            adapter.SelectCommand = cmd;
            try
            {
                conn.Open();
                adapter.Fill(dt);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
            finally
            {
                conn.Close();
            }
            return dt;
        }
 
        private void btn_Clear_Click(object sender, EventArgs e)
        {
            // this.dgvDemo.DataSource = null会将DataGridView的列也删掉
            //this.dgvDemo.DataSource = null;
 
            // 会报错：提示“不能清除此列表”
            //this.dgvDemo.Rows.Clear();
 
            DataTable dt = this.dgvDemo.DataSource as DataTable;
            dt.Rows.Clear();
            this.dgvDemo.DataSource = dt;
        }
    }
}