ConnectionString 属性尚未初始化。求大神帮助~~

[SkyAngela1989]

ConnectionString 属性尚未初始化。
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。

异常详细信息: System.InvalidOperationException: ConnectionString 属性尚未初始化。

源错误:


行 42: try
行 43: {
行 44: sda.Fill(ds);
行 45: }
行 46: catch (SqlException e)


源文件: c:\Inetpub\wwwroot\GD_Test\App_Code\Db.cs 行: 44

堆栈跟踪:


[InvalidOperationException: ConnectionString 属性尚未初始化。]
System.Data.SqlClient.SqlConnection.PermissionDemand() +941579
System.Data.SqlClient.SqlConnectionFactory.PermissionDemand(DbConnection outerConnection) +22
System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) +105
System.Data.SqlClient.SqlConnection.Open() +111
System.Data.Common.DbDataAdapter.FillInternal(DataSet dataset, DataTable[] datatables, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) +121
System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) +137
System.Data.Common.DbDataAdapter.Fill(DataSet dataSet) +86
GD.Db.ExecuteSelectSql(String sqlSelect) in c:\Inetpub\wwwroot\GD_Test\App_Code\Db.cs:44
GD.AdminTeacher.Page_Load(Object sender, EventArgs e) in c:\Inetpub\wwwroot\GD_Test\AdminTeacher.aspx.cs:24
System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +15
System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +33
System.Web.UI.Control.OnLoad(EventArgs e) +99
System.Web.UI.Control.LoadRecursive() +47
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1061




--------------------------------------------------------------------------------
版本信息: Microsoft .NET Framework 版本:2.0.50727.1891; ASP.NET 版本:2.0.50727.1879




web.config里面的连接代码是：
<appSettings/>
<!--
数据库连接字符串
-->
<connectionStrings>
<add name="ConnectionString" connectionString="data source=.\SQLEXPRESS;initial catalog=GD;persist security info=True;user id=sa;pwd=sa;packet size=4096"/>
</connectionStrings>

<system.web>



Db.cs中的代码是：
protected static string connString = ConfigurationManager.AppSettings["ConnectionString"];

public Db()
{
}

/// <summary>
/// 执行select类型的sql语句,返回select得到的数据集
/// </summary>
/// <param name="sqlSelect">select语句</param>
/// <returns>返回select得到的数据集</returns>
public static DataSet ExecuteSelectSql(string sqlSelect)
{
SqlConnection conn = new SqlConnection(connString);
SqlDataAdapter sda = new SqlDataAdapter(sqlSelect, conn);
DataSet ds = new DataSet();
try
{
sda.Fill(ds);
}
catch (SqlException e)
{
throw new Exception(e.Message);
}
return ds;
}




调试了很久~~ 新手求帮助啊~！！！

[风之影子]

protected static string connString = ConfigurationManager.AppSettings["ConnectionString"];


看看是否返回值了。

[三石-gary]

<add name="ConnectionString" 换个名字试试

[lqkankan]

ConfigurationManager.AppSettings["ConnectionString"];
用的不对

[SkyAngela1989]

......还是一样的报错噢~~

[lqkankan]

<appSettings>
<add key="aaa" value="aaa"/>
</appSettings>
<connectionStrings>
<add name="HY_XYKHEntities" connectionString="metadata=res://*/EFModel.csdl|res://*/EFModel.ssdl|res://*/EFModel.msl;provider=System.Data.SqlClient;provider connection string="Data Source=192.168.123.16;Initial Catalog=HY_XYKH;User ID=sa;Password=123456;MultipleActiveResultSets=True"" providerName="System.Data.EntityClient" />
</connectionStrings>


ConfigurationManager.AppSettings["ConnectionString"];

是读取 <appSettings>
<add key="aaa" value="aaa"/>
</appSettings>

节点里的值的

[SkyAngela1989]

那这个应该怎么用呢~~ [Quote=引用 3 楼 的回复:]
ConfigurationManager.AppSettings["ConnectionString"];
用的不对
[/Quote]

[lqkankan]

你写的是 <connectionStrings> 节点

要用 ConfigurationManager.ConnectionStrings["ConnectionString"]

[lqkankan]

你应该用 System.Configuration.ConfigurationManager.ConnectionStrings[""]

[dalmeeme]

很明显，你的连接字符串是写在<connectionStrings></connectionStrings>之间的，应该改成这样：

protected static string connString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;

[SkyAngela1989]

我那个web.config里面只有一个<appSetting/>，我添加一个<appSetting>后又出现节点add错误。。。[Quote=引用 5 楼 的回复:]
<appSettings>
<add key="aaa" value="aaa"/>
</appSettings>
<connectionStrings>
<add name="HY_XYKHEntities" connectionString="metadata=res://*/EFModel.csdl|res://*/EFModel.ssdl|res://*/EFMod……
[/Quote]

[fanbingyuan]

protected static string connString = ConfigurationManager.ConnectionStrings[""].ConnectionString;

[SkyAngela1989]

感谢 ~~~ 解决了···
谢谢各位的帮助~~~。。。
[Quote=引用 9 楼 的回复:]
很明显，你的连接字符串是写在<connectionStrings></connectionStrings>之间的，应该改成这样：

protected static string connString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
[/Quote]