datagrid控件建立稳固的双向排序

大家都知道DataGrid控件带有内置的事件来对记录进行排序,用户可单击列标题，就会按照相应的列进行排序,使用

非常方便和简单化.

但是它也有很大的不足,就是由datagrid代理的分页功能，只能单向排序，而且换页后，排序信息就会丢失.所以我

们需要改进一下分页的事件函数,利用状态包ViewState变量,达到能稳固的双向排序。:)


(1)首先在页面load时.要读取数据源里的数据,并将其送入到DataGrid

private void page_load(Object obj,EventArgs e)
{
  if(!Page.IsPostBack)
   {
    DataLoad();
    }
}

private void DataLoad()
{
     string connstr=ConfigurationSettings.AppSettings["ConnectionString"];
     OleDbConnection conn=new  OleDbConnection(connstr);
     DataSet ds=new DataSet();

     string sql;

if(ViewState["sorting"]==null)
    {
    sql="select * from userinfo";
    Response.Write(sql);
    }
  else
    {
    sql="select * from userinfo order by "+ViewState["sorting"].ToString()+"

"+ViewState["sortdirection"].ToString();
    Response.Write(sql);
    }

     OleDbDataAdapter da=new OleDbDataAdapter(sql,conn);
     da.Fill(ds);
     DataView dv=new DataView(ds.Tables[0]);
     grid1.DataSource=dv;
     grid1.DataBind();
}

(2)然后在datagrid控件的属性设定中加入如下选项;

...
allowpaging="true"
pagesize=13
pagerstyle-mode=numericpages
onpageindexchanged="changepage"
...

其中allowpaging="true",表示将启用分页功能,每页的大小，我们设定小一些(pagesize=13)，好让它多分页.
pagerstyle-mode=numericpages是将分页模式设为数字,最后指定了事件的处理程序为changepage方法.


private void changepage(Object obj,DataGridPageChangedEventArgs e)
{
 grid1.CurrentPageIndex=e.NewPageIndex;//当前页等于新的页面
 DataLoad();
}

(3)最后是排序的事件函数:
private void grid_sort(Object obj,DataGridSortCommandEventArgs e)
{
ViewState.Add("sorting",e.SortExpression);
if (ViewState["sortdirection"]==null)
  ViewState.Add("sortdirection","ASC");
else
{
    if(ViewState["sortdirection"].ToString()=="ASC")
      ViewState["sortdirection"]="DESC";
    else
 ViewState["sortdirection"]="ASC";
}
DataLoad();
}
<%@page language="C#"%>
<%@import namespace="System.Data"%>
<%@import namespace="System.Data.OleDb"%>

<script language="c#" runat="server">

private void page_load(Object obj,EventArgs e)
{
  if(!Page.IsPostBack)
   {
    DataLoad();
    }
}

private void DataLoad()
{
     string connstr=ConfigurationSettings.AppSettings["ConnectionString"];
     OleDbConnection conn=new  OleDbConnection(connstr);
     DataSet ds=new DataSet();

     string sql;

if(ViewState["sorting"]==null)
    {
    sql="select * from userinfo";
    Response.Write(sql);
    }
  else
    {
    sql="select * from userinfo order by "+ViewState["sorting"].ToString()+"

"+ViewState["sortdirection"].ToString();
    Response.Write(sql);
    }

     OleDbDataAdapter da=new OleDbDataAdapter(sql,conn);
     da.Fill(ds);
     DataView dv=new DataView(ds.Tables[0]);
     grid1.DataSource=dv;
     grid1.DataBind();
}


private void changepage(Object obj,DataGridPageChangedEventArgs e)
{
 grid1.CurrentPageIndex=e.NewPageIndex;//当前页等于新的页面
 DataLoad();
}


private void grid_sort(Object obj,DataGridSortCommandEventArgs e)
{
ViewState.Add("sorting",e.SortExpression);
if (ViewState["sortdirection"]==null)
  ViewState.Add("sortdirection","ASC");
else
{
    if(ViewState["sortdirection"].ToString()=="ASC")
      ViewState["sortdirection"]="DESC";
    else
 ViewState["sortdirection"]="ASC";
}
DataLoad();
}
</script>

<form runat="server">

<asp:datagrid )%></span>
</itemtemplate>
</asp:templatecolumn>

</columns>
</asp:datagrid>
</form>