protected void delectAll_Click(object sender, EventArgs e)
        {
            delectAll.Attributes.Add("onClick", "javascript:return confirm('确定删除吗？');");

            SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["new_conn"].ConnectionString);
            SqlCommand cmd;
            for (int i = 0; i < GridView1.Rows.Count; i++)
            {
                CheckBox cb = (CheckBox)GridView1.Rows[i].FindControl("CheckBox1");
                if (cb.Checked == true)
                {
                    cmd = new SqlCommand("delete from News where News_id='" + GridView1.DataKeys[i].Value + "'", conn);
                    conn.Open();
                    cmd.ExecuteNonQuery();
                    conn.Close();
                }
            } 

           Data_Bind();
        }