在实际的应用中经常会遇到根据其它列计算某一新列的结果，实现这样的功能有两种办法：一个直接使用sql语句；另外就是在绑定时进行动态添加。第一种方法以前已经介绍过。下面就是第二种方法的具体实现：
adddatasetcolumn.aspx
<![CDATA[<%@ page language="vb" autoeventwireup="false" codebehind="adddatasetcolumn.<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>x.vb”<br />
inherits=”<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>xweb.adddatasetcolumn”%><br />
<!doctype html public "-//w3c//dtd html 4.0 transitional//en"><br />
<html><br />
<head><br />
<title>adddatasetcolumn</title><br />
<meta name="generator" content="microsoft visual studio .net 7.1"><br />
<meta name="code_language" content="visual basic .net 7.1"><br />
<meta name="vs_defaultclientscript" content="javascript"><br />
<meta name="vs_targetschema" content="http://schemas.microsoft.com/intellisense/ie5"><br />
</head><br />
<body ms_positioning="gridlayout"></p>
<form id="form1" method="post" runat="server">
<<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:datagrid id=”datagrid1″ runat=”server” autogeneratecolumns=”false”<br />
showfooter=”true” width=”100%”><br />
<headerstyle font-names="宋体" font-bold="true" horizontalalign="center"
forecolor="navy" backcolor="lightsalmon"></headerstyle>
<footerstyle backcolor="#ffccff"></footerstyle>
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<<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:templatecolumn headertext=”订单号”><br />
<itemtemplate><br />
<<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:label id=”orderid” runat=”server”></<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:label><br />
</itemtemplate><br />
</<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:templatecolumn><br />
<<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:templatecolumn headertext=”产品号”><br />
<itemtemplate><br />
<<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:label id=”productid” runat=”server”></<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:label><br />
</itemtemplate><br />
</<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:templatecolumn><br />
<<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:templatecolumn headertext=”单价”><br />
<itemtemplate><br />
<<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:label id=”unitprice” runat=”server”></<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:label><br />
</itemtemplate><br />
</<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:templatecolumn><br />
<<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:templatecolumn headertext=”数量”><br />
<itemtemplate><br />
<<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:label id=”quantity” runat=”server”></<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:label><br />
</itemtemplate><br />
</<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:templatecolumn><br />
<<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:templatecolumn headertext=”折扣”><br />
<itemtemplate><br />
<<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:label id=”discount” runat=”server”></<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:label><br />
</itemtemplate><br />
</<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:templatecolumn><br />
<<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:templatecolumn headertext=”总计”><br />
<itemtemplate><br />
<<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:label id=”lbltotal” runat=”server”></<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:label><br />
</itemtemplate><br />
</<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:templatecolumn><br />
</columns>
</<a href="http://www.west999.com/www/go/?url=http://www.chinaitpower.com/dev/web/asp/index.html" target="_blank" rel="nofollow" >asp</a>:datagrid><br />
</form>
<p> </body><br />
</html><br />
]]>
adddatasetcolumn.aspx.vb
<![CDATA[imports system.web.ui.webcontrols</p>
<p>public class adddatasetcolumn<br />
inherits system.web.ui.page</p>
<p>#region ” web 窗体设计器生成的代码 ”</p>
<p> 该调用是 web 窗体设计器所必需的。<br />
<system.diagnostics.debuggerstepthrough()> private sub initializecomponent()</p>
<p> end sub<br />
protected withevents datagrid1 as system.web.ui.webcontrols.datagrid</p>
<p> 注意: 以下占位符声明是 web 窗体设计器所必需的。<br />
不要删除或移动它。<br />
private designerplaceholderdeclaration as system.object</p>
<p> private sub page_init(byval sender as system.object, byval e as system.eventargs) handles mybase.init<br />
codegen: 此方法调用是 web 窗体设计器所必需的<br />
不要使用代码编辑器修改它。<br />
initializecomponent()<br />
end sub</p>
<p>#end region</p>
<p> private sub page_load(byval sender as system.object, byval e as system.eventargs) handles mybase.load<br />
dim strcnn as string = “data source=.\netsdk; initial catalog=northwind;user id=sa;password=;”<br />
dim ocn as new system.data.sqlclient.sqlconnection(strcnn)<br />
dim strsql as system.string = “select * from [order details]”<br />
dim ds as system.data.dataset = new system.data.dataset<br />
ocn.open()<br />
dim da as system.data.sqlclient.sqldataadapter = new system.data.sqlclient.sqldataadapter(strsql, ocn)<br />
可以直接使用sql语句实现，这个方法可以直接绑定，不需要用模板即可<br />
cmd.commandtext = “select *,unitprice * quantity *(1- discount) as total from [order details]”<br />
我们使用另外一种方法，在datagrid绑定之前为dataset添加一个列<br />
da.fill(ds, “ds”)<br />
dim dvwgrid as dataview = ds.tables(0).defaultview<br />
datagrid1.datasource = dvwgrid<br />
datagrid1.databind()<br />
ocn.close()<br />
ocn.dispose()<br />
end sub</p>
<p> private sub datagrid1_itemdatabound(byval sender as object, byval e as datagriditemeventargs) _<br />
handles datagrid1.itemdatabound<br />
dim elemtype as listitemtype = e.item.itemtype<br />
if (elemtype = listitemtype.item or elemtype = listitemtype.alternatingitem) then<br />
把dataitem转换回datarowview对象<br />
dim mydatarowview as datarowview = ctype(e.item.dataitem, datarowview)<br />
dim mydatarow as datarow = mydatarowview.row<br />
ctype(e.item.cells(0).findcontrol(“orderid”), label).text = mydatarow(“orderid”)<br />
ctype(e.item.cells(1).findcontrol(“productid”), label).text = mydatarow(“productid”)<br />
ctype(e.item.cells(2).findcontrol(“unitprice”), label).text = mydatarow(“unitprice”)<br />
ctype(e.item.cells(3).findcontrol(“quantity”), label).text = mydatarow(“quantity”)<br />
ctype(e.item.cells(4).findcontrol(“discount”), label).text = mydatarow(“discount”)</p>
<p> dim dblprice as double = double.parse(mydatarow(“unitprice”))<br />
dim intquantity as integer = int32.parse(mydatarow(“quantity”))<br />
dim intdiscount as double = double.parse(mydatarow(“discount”))</p>
<p> dim ntotal as string = string.format(“{0:c}”, dblprice * (1 – intdiscount) * intquantity)<br />
ctype(e.item.cells(5).findcontrol(“lbltotal”), label).text = ntotal<br />
end if<br />
end sub<br />
end class<br />
]]>
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