对GridView兑现分页

对GridView实现分页

前台代码:

         <table>
             <tr>
                 <td>
                       <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False">
            <Columns>
                <asp:BoundField DataField="Id" HeaderText="编号" />
                <asp:BoundField DataField="NewsTitle" HeaderText="标题" />
                <asp:BoundField DataField="NewsContent" HeaderText="内容" />
                <asp:BoundField DataField="RealName" HeaderText="创建者" />
                <asp:BoundField DataField="CreateTime" DataFormatString="{0:yyyy-mm-dd hh:mm:ss}" HeaderText="创建时间" />
                <asp:BoundField DataField="ClassName" HeaderText="类型" />
            </Columns>
        </asp:GridView>
                 </td>
             </tr>
             <tr>
                 <td>
                     <asp:LinkButton ID="lbtnFirst" runat="server" OnClick="lbtnFirst_Click">第一页</asp:LinkButton>
                     <asp:LinkButton ID="lbtnProc" runat="server" OnClick="lbtnProc_Click">上一页</asp:LinkButton>
                     <asp:LinkButton ID="lbtnNext" runat="server" OnClick="lbtnNext_Click">下一页</asp:LinkButton>
                     <asp:LinkButton ID="lbtnLast" runat="server" OnClick="lbtnLast_Click">最后一页</asp:LinkButton>
                 </td>
             </tr>
         </table>

后台代码:

        string constr = "data source=.;initial catalog=News;user id=sa;password=111111;";
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                ViewState["pageIndex"] = 1;
                DataPage();

            }
        }

        private void DataPage()
        {
            SqlConnection conn = new SqlConnection(constr);
            conn.Open();
            SqlCommand cmd = conn.CreateCommand();
           // string sql = "select T1.Id,T1.NewsTitle,SUBSTRING(T1.NewsContent,0,20) as NewsContent,T2.RealName ,T1.CreateTime,T3.ClassName from T_News1 T1 join T_User T2 on T1.NewsCreator=T2.UserId join T_NewsClass T3 on T1.ClassId=T3.ClassId";
            string sql = "   select T1.Id,T1.NewsTitle,SUBSTRING(T1.NewsContent,0,20) as NewsContent,T2.RealName,T1.CreateTime,T3.ClassName  from (select ROW_NUMBER() over (order by Id) as rownumber,* from T_News) T1 join T_User T2 on T1.NewsCreator=T2.UserId join T_NewsClass  T3 on T1.ClassId=T3.ClassId where  rownumber>(@pageIndex-1)*@pageSize and rownumber<=@pageIndex*@pageSize";
            cmd.Parameters.AddWithValue("@pageSize", 3);
            cmd.Parameters.AddWithValue("@pageIndex", Convert.ToInt32(ViewState["pageIndex"]));
            cmd.CommandText = sql;
            SqlDataAdapter adapter = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            adapter.Fill(dt);

            string sql1 = "select count(*) from T_News";
            cmd.CommandText = sql1;
            int i =Convert.ToInt32(cmd.ExecuteScalar());
            if (i % 3 == 0)
            {
                ViewState["pageCount"] = i / 3;
            }
            else
            { ViewState["pageCount"] = i / 3+1; }
            conn.Close();
            conn.Dispose();

            GridView1.DataSource = dt;
            GridView1.DataBind();
        }

        protected void lbtnFirst_Click(object sender, EventArgs e)
        {
            ViewState["pageIndex"] = 1;
            DataPage();
        }

        protected void lbtnProc_Click(object sender, EventArgs e)
        {
            int i=Convert.ToInt32(ViewState["pageIndex"]) ;
            if (i>1)
            {
                i--;
                ViewState["pageIndex"] = i;
                DataPage();
            }
        }

        protected void lbtnNext_Click(object sender, EventArgs e)
        {
            int i = Convert.ToInt32(ViewState["pageIndex"]);
            if (i <Convert.ToInt32(ViewState["pageCount"]))
            {
                i++;
                ViewState["pageIndex"] = i;
                DataPage();
            }
        }

        protected void lbtnLast_Click(object sender, EventArgs e)
        {
            ViewState["pageIndex"] = ViewState["pageCount"];
            DataPage();
        }