Delete multiple pages in Asp.net gridview

Book_admin.aspx CopyCode The Code is as follows: <asp: dag id = "grwbook" runat = "server" cellpadding = "4" forecolor = "#333333" gridlines = "NONE" autogeneratecolumns = "false" allowpaging = "true" datakeynames =" ID "onpageindexchanging =" grwbook_pageindexchanging "pagesize =" 12 ">
<Footerstyle backcolor = "#507cd1" font-bold = "true" forecolor = "white"/>
<Rowstyle backcolor = "# eff3fb"/>
<Editrowstyle backcolor = "# 2461bf"/>
<Selectedrowstyle backcolor = "# d1ddf1" font-bold = "true" forecolor = "#333333"/>
<Pagerstyle backcolor = "# 2461bf" forecolor = "white" horizontalalign = "center"/>
<Headerstyle backcolor = "#507cd1" font-bold = "true" forecolor = "white"/>
<Alternatingrowstyle backcolor = "white"/>
<Columns>
<Asp: boundfield datafield = "ID" headertext = "ID"/>
<Asp: boundfield datafield = "username" headertext = "name">
<Itemstyle width = "60px"/>
</ASP: boundfield>
<Asp: boundfield datafield = "Comments" headertext = "comment">
<Itemstyle width = "500px"/>
</ASP: boundfield>
<Asp: boundfield datafield = "postdate" headertext = "date"/>
<Asp: hyperlinkfield datanavigateurlfields = "newsid" datanavigateurlformatstring = "../news_zi.asp? Id = {0} "headertext =" Article "Datatextfield =" newsid "target =" _ blank "/>
<Asp: templatefield headertext = "operation">
<Itemtemplate>
<Asp: checkbox runat = "server" id = "cbxid"/>
</Itemtemplate>
</ASP: templatefield>
</Columns>
<Pagersettings mode = "nextpreviusfirstlast" firstpagetext = "first page" lastpagetext = "last page" nextpagetext = "next page" previouspagetext = "Previous Page"/>
</ASP: gridview>

Book_admin.aspx.csCopy codeThe Code is as follows: using system;
Using system. Data;
Using system. configuration;
Using system. collections;
Using system. Web;
Using system. Web. Security;
Using system. Web. UI;
Using system. Web. UI. webcontrols;
Using system. Web. UI. webcontrols. webparts;
Using system. Web. UI. htmlcontrols;
Using system. Data. oledb;

Public partial class admin_book_admin: system. Web. UI. Page
{

Protected void page_load (Object sender, eventargs E)
{
// Determine whether the Administrator has logged on
Admin. checkadmin ();

Btndel. Attributes. Add ("onclick", "Return confirm ('Are you sure you want to delete it? ')");

If (! Page. ispostback)
{
Datainit ();
}
}

Protected void grwbook_pageindexchanging (Object sender, gridviewpageeventargs E)
{
This. grwbook. pageindex = E. newpageindex;
Session ["curretnpage"] = E. newpageindex;
Datainit ();
}

// Data Binding
Private void datainit ()
{
Dataset DS = dB. dataset ("select ID, username, comments, postdate, newsid from feedback order by postdate DESC, newsid DESC ");
If (viewstate ["currentpage"]! = NULL)
{
This. grwbook. pageindex = convert. toint32 (session ["currentpage"]);
}
This. grwbook. datasource = Ds;
This. grwbook. databind ();

}

// Perform the delete operation
Protected void btndel_click (Object sender, eventargs E)
{
String sqltext = "(";
For (INT I = 0; I <grwbook. Rows. Count; I ++)
{
// Search for column 3 of row n
Checkbox cbx = (checkbox) grwbook. Rows [I]. findcontrol ("cbxid ");
If (cbx. Checked = true)
{
Sqltext = sqltext + convert. toint32 (grwbook. datakeys [I]. Value) + ",";
}
}

// Determine whether or not selected
If (sqltext! = "(")
{
// Remove the last comma and add parentheses
Sqltext = sqltext. substring (0, sqltext. Length-1) + ")";
Sqltext = "delete from feedback where ID in" + sqltext;
Try
{
// Execute the delete statement
DB. excutesql (sqltext );
// Rebind data
Common. salert ("deleted successfully ");
Datainit ();
// Response. Redirect ("book_admin.aspx ");
}
Catch (exception ex)
{
// If an error occurs, the error message is output.
Common. salert (ex. Message );
}
Finally
{

}
}
Else
{
Common. salert ("You have not selected a deleted item ");
}
}

}