异常详细信息: System.InvalidOperationException: ConnectionString 属性尚未初始化
1、运行环境：Visual studio2005
调试时无错，而连接数据库时报错：
异常详细信息: System.InvalidOperationException: ConnectionString 属性尚未初始化
2、源错误(250):

行 248:try
行 249:{
行 250:myConnection.Open();
行 251:myCommand.ExecuteNonQuery();
行 252:myConnection.Close();

堆栈跟踪:
[InvalidOperationException: ConnectionString 属性尚未初始化。]
System.Data.SqlClient.SqlConnection.PermissionDemand() +46
System.Data.SqlClient.SqlConnectionFactory.PermissionDemand(DbConnection outerConnection) +22
System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) +89
System.Data.SqlClient.SqlConnection.Open() +160
Bid.Person.Login(String strEmail, String strPassword) in e:\Visual Studio 2005\WebSites\WebSite4\App_Code\Person.cs:250
Default_aspx.btnSubmit_Click(Object sender, EventArgs e) in e:\Visual Studio 2005\WebSites\WebSite4\Default.aspx.cs:42
System.Web.UI.WebControls.Button.OnClick(EventArgs e) +75
System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +97
System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +7
System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +11
System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +33
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +4921

3、错误源代码段：
SqlConnection myConnection = new SqlConnection(ConfigurationManager.AppSettings[ "ConnectionString "]);
SqlCommand myCommand = new SqlCommand( "sp_person_isp ", myConnection);
HttpContext.Current.Trace.Write( "foo: " + ConfigurationManager.AppSettings[ "ConnectionString "]);
// Mark the Command as a SPROC
myCommand.CommandType = CommandType.StoredProcedure;

// Add Parameters to SPROC
SqlParameter prmEmail = new SqlParameter( "@email ", SqlDbType.VarChar, 255);
prmEmail.Value = emailaddress;
myCommand.Parameters.Add(prmEmail);

SqlParameter prmname = new SqlParameter( "@name ", SqlDbType.VarChar, 255);

prmname.Value = name;
myCommand.Parameters.Add(prmname);

SqlParameter prmcity = new SqlParameter( "@city ", SqlDbType.VarChar, 255);
prmcity.Value = city;
myCommand.Parameters.Add(prmcity);

SqlParameter prmcountry = new SqlParameter( "@country ", SqlDbType.VarChar, 255);
prmcountry.Value = country;
myCommand.Parameters.Add(prmcountry);

SqlParameter prmPersonID = new SqlParameter( "@personid ", SqlDbType.BigInt);
prmPersonID.Direction = ParameterDirection.Output;
myCommand.Parameters.Add(prmPersonID);

SqlParameter prmpwd = new SqlParameter( "@pwd ", SqlDbType.VarChar, 255);
prmpwd.Value = password;
myCommand.Parameters.Add(prmpwd);

try
{
myConnection.Open();
myCommand.ExecuteNonQuery();
myConnection.Close();

return prmPersonID.Value.ToString();
}
catch (SqlException SQLexc)
{
return SQLexc.ToString();
}

[解决办法]
<add key= "ConnectionString " value= "Data Source=.\SQLExpress;AttachDBFilename=|DataDirectory|BidData.mdf;Integrated Security=True;User Instance=True " />