关于ADO.NET连接的有关问题
日期：2014-05-19 浏览次数：20503 次
关于ADO.NET连接的问题
<%@ Page Language= "VB " %>
<%@ Import Namespace = "system.data " %>
<%@ Import Namespace = "system.data.sqlclient " %>
<%@ Import Namespace = "system.configuration " %>
<script runat= "server " >
Protected Sub Page_load(ByVal sender As Object, ByVal e As System.EventArgs)
If Not Page.IsPostBack Then
Dim conn As SqlConnection
Dim cmd As SqlCommand
Dim rd As SqlDataReader
conn = New SqlConnection()
conn.ConnectionString = ConfigurationManager.ConnectionStrings( "DSN_Northwind ").ConnectionString
cmd = New SqlCommand()
cmd.CommandText = "select top 3 * from customers "
cmd.CommandType = CommandType.Text
cmd.Connection = conn
cmd.Connection.Open()
rd = cmd.ExecuteReader(CommandBehavior.CloseConnection)
gvCustomers.datasource = rd
gvCustomers.databind()
cmd.Dispose()
conn.Dispose()
End If
End Sub
</script>
<html>
<head runat= "server ">
<title> 无标题页 </title>
</head>
<body>
<form id= "form1 " runat= "server ">
<div>
<asp:GridView ID= "gvCustomers " runat= "server ">
</asp:GridView>
</div>
</form>
asdfFFFDD
</body>
</html>
在vs2005中执行时，下面这行
conn.ConnectionString = ConfigurationManager.ConnectionStrings( "DSN_Northwind ").ConnectionString
报错。
错误提示如下：＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊
未将对象引用设置到对象的实例。
说明: 执行当前 Web 请求期间，出现未处理的异常。请检查堆栈跟踪信息，以了解有关该错误以及代码中导致错误的出处的详细信息。
异常
<%@ Page Language= "VB " %>
<%@ Import Namespace = "system.data " %>
<%@ Import Namespace = "system.data.sqlclient " %>
<%@ Import Namespace = "system.configuration " %>
<script runat= "server " >
Protected Sub Page_load(ByVal sender As Object, ByVal e As System.EventArgs)
If Not Page.IsPostBack Then
Dim conn As SqlConnection
Dim cmd As SqlCommand
Dim rd As SqlDataReader
conn = New SqlConnection()
conn.ConnectionString = ConfigurationManager.ConnectionStrings( "DSN_Northwind ").ConnectionString
cmd = New SqlCommand()
cmd.CommandText = "select top 3 * from customers "
cmd.CommandType = CommandType.Text
cmd.Connection = conn
cmd.Connection.Open()
rd = cmd.ExecuteReader(CommandBehavior.CloseConnection)
gvCustomers.datasource = rd
gvCustomers.databind()
cmd.Dispose()
conn.Dispose()
End If
End Sub
</script>
<html>
<head runat= "server ">
<title> 无标题页 </title>
</head>
<body>
<form id= "form1 " runat= "server ">
<div>
<asp:GridView ID= "gvCustomers " runat= "server ">
</asp:GridView>
</div>
</form>
asdfFFFDD
</body>
</html>
在vs2005中执行时，下面这行
conn.ConnectionString = ConfigurationManager.ConnectionStrings( "DSN_Northwind ").ConnectionString
报错。
错误提示如下：＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊
未将对象引用设置到对象的实例。
说明: 执行当前 Web 请求期间，出现未处理的异常。请检查堆栈跟踪信息，以了解有关该错误以及代码中导致错误的出处的详细信息。
异常
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