string id_s = "";
            for (int i = 0; i < dataGridView1.Rows.Count; i++) //遍历所有行
            {
                if (dataGridView1.Rows[i].Cells["stu_sno"].Value != null) //要获得的学号不能为空
                {
                    if (dataGridView1.Rows[i].Cells[0].EditedFormattedValue.ToString() == "True")//是否勾选
                    {
                        id_s += "," + dataGridView1.Rows[i].Cells["stu_sno"].Value.ToString();//添加学号到字符串
                    }
                }
            }
            string sqlconn = "server=.;database=student;integrated security=true";
            try
            {
                id_s = id_s.Substring(1); //截取","号
                string sqlcomm = "delete from student_info where stu_sno in (" + id_s + ")";
                SqlConnection conn = new SqlConnection(sqlconn);
                SqlCommand cmd = new SqlCommand(sqlcomm, conn);
                conn.Open();
                cmd.ExecuteNonQuery();
                conn.Close();
                MessageBox.Show("批量删除成功");
            }
            catch (Exception a)
            {
                MessageBox.Show(a.ToString());
            }