在Ajax里面不能用ConfigurationManager吗？

Question

 请问各位大侠，在Ajax里面不能用ConfigurationManager吗？ 我建的是Ajax网站，用的是三层架构，在数据层添加了SQLHelper，但是 ConfigurationManager 报错，当前上下文中不存在名称 onfigurationManager ，我都已经手动引用了System.Configuration ，但还是不行。请各位大侠帮帮忙，想想办法。谢谢。using System;
using System.Data;
using System.Configuration;
using System.Data.SqlClient;
using System.Collections;namespace DAL
{    
    public abstract class SqlHelper
    {        
        public static readonly string constr = ConfigurationManager.ConnectionStrings["SQLConnString1"].ConnectionString;
        
        private static Hashtable parmCache = Hashtable.Synchronized(new Hashtable());        public static int ExecuteNonQuery(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {            SqlCommand cmd = new SqlCommand();            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
                int val = cmd.ExecuteNonQuery();
                cmd.Parameters.Clear();
                return val;
            }
        }
        
        public static int ExecuteNonQuery(SqlConnection connection, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {            SqlCommand cmd = new SqlCommand();            PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
            int val = cmd.ExecuteNonQuery();
            cmd.Parameters.Clear();
            return val;
        }        public static int ExecuteNonQuery(SqlTransaction trans, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();
            PrepareCommand(cmd, trans.Connection, trans, cmdType, cmdText, commandParameters);
            int val = cmd.ExecuteNonQuery();
            cmd.Parameters.Clear();
            return val;
        }        public static SqlDataReader ExecuteReader(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();
            SqlConnection conn = new SqlConnection(connectionString);            try
            {
                PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
                SqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                cmd.Parameters.Clear();
                return rdr;
            }
            catch
            {
                conn.Close();
                throw;
            }
        }
        
        public static object ExecuteScalar(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {
            SqlCommand cmd = new SqlCommand();            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
                object val = cmd.ExecuteScalar();
                cmd.Parameters.Clear();
                return val;
            }
        }        public static object ExecuteScalar(SqlConnection connection, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
        {            SqlCommand cmd = new SqlCommand();            PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
            object val = cmd.ExecuteScalar();
            cmd.Parameters.Clear();
            return val;
        }
        
        public static void CacheParameters(string cacheKey, params SqlParameter[] commandParameters)
        {
            parmCache[cacheKey] = commandParameters;
        }
        
        public static SqlParameter[] GetCachedParameters(string cacheKey)
        {
            SqlParameter[] cachedParms = (SqlParameter[])parmCache[cacheKey];            if (cachedParms == null)
                return null;            SqlParameter[] clonedParms = new SqlParameter[cachedParms.Length];            for (int i = 0, j = cachedParms.Length; i < j; i++)
                clonedParms[i] = (SqlParameter)((ICloneable)cachedParms[i]).Clone();            return clonedParms;
        }        private static void PrepareCommand(SqlCommand cmd, SqlConnection conn, SqlTransaction trans, CommandType cmdType, string cmdText, SqlParameter[] cmdParms)
        {            if (conn.State != ConnectionState.Open)
                conn.Open();            cmd.Connection = conn;
            cmd.CommandText = cmdText;            if (trans != null)
                cmd.Transaction = trans;            cmd.CommandType = cmdType;            if (cmdParms != null)
            {
                foreach (SqlParameter parm in cmdParms)
                    cmd.Parameters.Add(parm);
            }
        }
    }
}

Answer 1

 就是添加引用。我都已经添加了，可还不不能通过编译。是不是在ajax网站中的配置文件有问题了，我的不是用ajax建的网站里面又是可以用的，能通过编译的。
  但是在ajax网站里面不能通过编译，又该怎么办了，各位大侠帮忙看看吧！！

Answer 2

public static readonly string constr = ConfigurationManager.ConnectionStrings["SQLConnString1"].ConnectionString;
就是这句的ConfigurationManager在上下文中找不到。

Answer 3

用WebConfigurationManager 试试？

Answer 4

using System.Configuration;
ConfigurationManager
添加WEB引用

Answer 5

System.Configuration
在引用的时候把这个命名空间的dll加进来