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();         }