using System;

using System.Collections;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Web;

using System.Web.SessionState;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.HtmlControls;

using System.Data.OleDb;

using System.Text;

 

namespace Paging

{

    public class FastPaging_DataSet : System.Web.UI.Page

    {

        protected System.Web.UI.WebControls.DataGrid DataGrid1;

 

        const String QUERY_FIELDS       = "*";          //要查询的字段

        const String TABLE_NAME     = "订单明细表"; //数据表名称

        const String PRIMARY_KEY        = "ID";         //主键字段

        const String DEF_ORDER_TYPE = "ASC";            //默认排序方式

        const String SEC_ORDER_TYPE = "DESC";       //可选排序方式

        const String CONDITION      = "产品ID='AV-CB-1'";

 

        OleDbConnection conn;

        OleDbCommand cmd;

        OleDbDataAdapter da;

 

        #region 属性

 

        #region CurrentPageIndex

        /// <summary>

        /// 获取或设置当前页的索引。

        /// </summary>

        public int CurrentPageIndex

        {

            get { return (int) ViewState["CurrentPageIndex"]; }

            set { ViewState["CurrentPageIndex"] = value; }

        }

        #endregion

 

        #region OrderType

        /// <summary>

        /// 获取排序的方式：升序（ASC）或降序（DESC）。

        /// </summary>

        public String OrderType

        {

            get {

                String orderType = DEF_ORDER_TYPE;

                if (ViewState["OrderType"] != null) {

                    orderType = (String)ViewState["OrderType"];

                    if (orderType != SEC_ORDER_TYPE)

                        orderType = DEF_ORDER_TYPE;

                }

                return orderType;

            }

            set { ViewState["OrderType"] = value.ToUpper(); }

        }

        #endregion

 

        #endregion

   

        private void Page_Load(object sender, System.EventArgs e)

        {

            #region 实现

            String strConn = "PROVIDER=Microsoft.Jet.OLEDB.4.0;Data Source="

                + Server.MapPath("Northwind.mdb");

            conn = new OleDbConnection(strConn);

            cmd = new OleDbCommand("",conn);

            da = new OleDbDataAdapter(cmd);

 

            if (!IsPostBack) {

                // 设置用于自动计算页数的记录总数

                DataGrid1.VirtualItemCount = GetRecordCount(TABLE_NAME);

 

                CurrentPageIndex = 0;

                BindDataGrid();

            }

            #endregion

        }

 

        #region Web 窗体设计器生成的代码

        override protected void OnInit(EventArgs e)

        {

            //

            // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。

            //

            InitializeComponent();

            base.OnInit(e);

        }

       

        /// <summary>

        /// 设计器支持所需的方法 - 不要使用代码编辑器修改

        /// 此方法的内容。

        /// </summary>

        private void InitializeComponent()

        {   

            this.Load += new System.EventHandler(this.Page_Load);

        }

        #endregion

 

        private void BindDataGrid()

        {

            #region 实现

            // 设置当前页的索引

            DataGrid1.CurrentPageIndex = CurrentPageIndex;

            // 设置数据源

            DataGrid1.DataSource = GetDataView();

            DataGrid1.DataBind();

            #endregion

        }

 

        /// <summary>

        /// 取得数据库表中的记录总数。

        /// </summary>

        /// <param name="tableName">数据库中的表的名称。</param>

        /// <returns>成功则为表中记录的总数；否则为 -1。</returns>

        private int GetRecordCount(string tableName)

        {

            #region 实现

            int count;

            cmd.CommandText = "SELECT COUNT(*) AS RecordCount FROM " + tableName;

            try {

                conn.Open();

                count = Convert.ToInt32(cmd.ExecuteScalar());

            } catch(Exception ex) {

                Response.Write (ex.Message.ToString());

                count = -1;

            } finally {

                conn.Close();

            }

            return count;

            #endregion

        }

 

        private DataView GetDataView()

        {

            #region 实现

            int pageSize = DataGrid1.PageSize;

            DataSet ds = new DataSet();

            DataView dv = null;

           

            cmd.CommandText = FastPaging.Paging(

                pageSize,

                CurrentPageIndex,

                DataGrid1.VirtualItemCount,

                TABLE_NAME,

                QUERY_FIELDS,

                PRIMARY_KEY,

                FastPaging.IsAscending(OrderType) );

 

            try {

                da.Fill(ds, TABLE_NAME);

                dv = ds.Tables[0].DefaultView;

            } catch(Exception ex) {

                Response.Write (ex.Message.ToString());

            }

            return dv;

            #endregion

        }

 

        protected void MyDataGrid_Page(Object sender, DataGridPageChangedEventArgs e)

        {

            CurrentPageIndex = e.NewPageIndex;

            BindDataGrid();

        }

 

        protected void DataGrid1_SortCommand(object source, DataGridSortCommandEventArgs e)

        {

            #region 实现

            DataGrid1.CurrentPageIndex = 0;

            this.CurrentPageIndex = 0;

 

            if (OrderType == DEF_ORDER_TYPE)

                OrderType = SEC_ORDER_TYPE;

            else

                OrderType = DEF_ORDER_TYPE;

 

            BindDataGrid();

            #endregion

        }

    }

}