异常详细信息: System.NullReferenceException: 未将对象引用设置到对象的实例。请问我哪里弄错啦 为什么一点击登录就出错

[寒晓浴伊]

web.config代码
<?xml version="1.0"?>
<configuration>
<system.web>
<compilation debug="true" targetFramework="4.0" />
</system.web>
<appSettings>
<add key="SqlConnStrName" value="server=.;database=tradeDVDDB;Integrated Security=SSPI"/>
</appSettings>
</configuration>


PublicClass代码
using System;
using System.Data;
using System.Configuration;
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.SqlClient;

public class PublicClass
{
public static bool ExecuteSQL(string SQLState)
{

string sqlConnStr = ConfigurationManager.ConnectionStrings["SqlConnStrName"].ConnectionString;
SqlConnection sqlConn = new SqlConnection();
sqlConn.ConnectionString = sqlConnStr;
sqlConn.Open();
SqlCommand sqlCmd = new SqlCommand();
sqlCmd.Connection = sqlConn;
sqlCmd.CommandType = CommandType.Text;
sqlCmd.CommandText = SQLState;
try
{
sqlCmd.ExecuteNonQuery();
return true;
}
catch (Exception e)
{
return false;
}
finally
{
sqlConn.Close();
}
}
public static DataSet returnDS(string SQLState)
{
string sqlConnStr = ConfigurationManager.ConnectionStrings["SqlConnStrName"].ConnectionString;//这里是出现问题的地方 说没有实例 哪里错啦 该怎么改啊
SqlConnection sqlConn = new SqlConnection();
sqlConn.ConnectionString = sqlConnStr;
sqlConn.Open();
SqlCommand sqlCmd = new SqlCommand();
sqlCmd.Connection = sqlConn;
sqlCmd.CommandType = CommandType.Text;
sqlCmd.CommandText = SQLState;
SqlDataAdapter sqlDA = new SqlDataAdapter();
sqlDA.SelectCommand = sqlCmd;
DataSet sqlDS = new DataSet();
sqlDA.Fill(sqlDS);
return sqlDS;
}
}

[正怒月神]

PublicClass从app_Code移到其他文件夹，试试看。

[ajianchina]

你复制过去吧 <?xml version="1.0"?> <configuration> <system.web> <compilation debug="true" targetFramework="4.0" /> </system.web> <connectionStrings> <add name="SqlConnStrName" connectionString="server=.;database=tradeDVDDB;Integrated Security=SSPI"/> </connectionStrings> </configuration>

[正怒月神]

2楼正解。
仔细看了一下，
的确节点放错了。