ds查询符合条件记录

注意：

dataset 的clone是浅克隆  copy是深克隆

private void Page_Load(object sender, System.EventArgs e)
{
        if(!Page.IsPostBack)
 {
  MySqlConnection conn = new MySqlConnection("User Id=root;Password=sa;Host=localhost;Database=mis;");
  conn.Open();
  MySqlDataAdapter da = new MySqlDataAdapter("select id, name, age from users ",conn);
  DataSet ds =new DataSet();
  da.Fill(ds,"users");
  conn.Close();
  DataGrid1.DataSource= ds;
  DataGrid1.DataBind();
  Session["a"] = ds;
 }
}

private void Button3_Click(object sender, System.EventArgs e)
{
 DataSet ds1 = new DataSet();
 ds1 = ((DataSet)Session["a"]).Copy();
 DataRow[] foundRows = ds1.Tables[0].Select("id>10");
 foreach(DataRow r in foundRows)
 {
  ds1.Tables[0].Rows.Remove(r);
 }
 DataGrid1.DataSource= ds1;
 DataGrid1.DataBind();
}

private void Button4_Click(object sender, System.EventArgs e)
{
 DataSet ds1 = new DataSet();
 ds1 = ((DataSet)Session["a"]).Copy();
 DataRow[] foundRows = ds1.Tables[0].Select("id>2");
 foreach(DataRow r in foundRows)
 {
  ds1.Tables[0].Rows.Remove(r);
 }
 DataGrid1.DataSource= ds1;
 DataGrid1.DataBind();
}