C#中Datagridview如何删除选中记录

private void DeleteBtn_Click(object sender, EventArgs e)
        {
            //string dbconn = ConfigurationManager.ConnectionStrings["connstr"].ConnectionString;(方法一)
            string dbconn = configxml.xmlconn.readxml(); //方法二
            SqlConnection sqlcon = new SqlConnection(dbconn);

            if (dataGridView1.DataSource == null || dataGridView1.CurrentRow == null)
            {
                   return;
            }
            else
            {
                if (this.dataGridView1.SelectedRows.Count > 0)
                {
                    DialogResult dr = MessageBox.Show("确定删除选中的记录 ", "提示",MessageBoxButtons.OKCancel, MessageBoxIcon.Question);
                    if (dr == DialogResult.OK)
                    {
                        try
                        {
                            sqlcon.Open();; //打开数据库连接
                            foreach (DataGridViewRow row in this.dataGridView1.SelectedRows) //遍历所选中的dataGridView记录行
                            {
                                string strName = row.Cells[1].Value.ToString(); //取dataGridView1中的第二列的值
                                string sql = string.Format("delete from T_users where username='{0}'", strName); //SQL语句来执行要求操作
                                SqlCommand cmd = new SqlCommand(sql, sqlcon); //执行sqlcommand的数据连接
                                cmd.ExecuteNonQuery(); //执行删除操作
                                cmd.Dispose();
                            }
                        }
                        catch (Exception ex)
                        {
                            MessageBox.Show(ex.ToString(), "提示");
                        }
                        finally
                        {
                            sqlcon.Close(); //关闭数据库连接
                        }
                        this.ButtonFresh_Click(this.t_usersTableAdapter.Fill(this.misds.T_users),null);
                        //删除后执行刷新操作ButtonFresh是刷新按钮的名字，刷新方法在此就不写了。
                    }
                    else
                    {
                        return;
                    }
                }
            }
        }
#endregion