在执行用户定义例程或聚合 'sp_sync_data' 期间出现 .NET Framework 错误: 
System.Security.SecurityException: Request for the permission of type 'System.Net.WebPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.
System.Security.SecurityException: 
   at StoredProcedures.SyncData()
。

using System;
using System.Data;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using Microsoft.SqlServer.Server;
using System.IO;
using System.Net;
using System.Text;
using System.Collections;
using System.Security.Permissions;

public partial class StoredProcedures
{
    [Microsoft.SqlServer.Server.SqlProcedure]
    public static void SyncData()
    {
        string conn_string = "context connection = true";
        string uri = "{0}?o={1}&r={2}";
        string sql = "select syncuri,oid,reservea from mydatatable";
        SqlDataAdapter sda = new SqlDataAdapter(sql, conn_string);
        try
        {
            DataTable dt = new DataTable();
            sda.Fill(dt);
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                string syncuri = dt.Rows[i]["syncuri"].ToString();
                string oid = dt.Rows[i]["oid"].ToString();
                string reservea = dt.Rows[i]["reservea"].ToString();
                string syncresult = GetHttpRequest(string.Format(uri, syncuri, oid, reservea));
                if (syncresult == "1")
                {
                    //etc
                }
            }
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }
    private static string GetHttpRequest(string uri)
    {
        #region 这样也不成，晕

         WebPermission oWebPermision = new WebPermission(PermissionState.None);
        oWebPermision.AddPermission(NetworkAccess.Connect, uri);
        oWebPermision.AddPermission(NetworkAccess.Accept, uri);
        oWebPermision.Demand();

        #endregion

        string strResult = string.Empty;
        WebRequest oRequest = null;
        WebResponse oResponse = null;
        StreamReader oStreamReader = null;
        try
        {
            oRequest = WebRequest.Create(uri);
            oRequest.ContentType = "application/x-www-form-urlencoded";
            oRequest.Method = "GET";
            oResponse = oRequest.GetResponse();
            oStreamReader = new StreamReader(oResponse.GetResponseStream(), Encoding.Default);
            strResult = oStreamReader.ReadToEnd();
            oStreamReader.Close();
            oStreamReader = null;
            oResponse.Close();
            oResponse = null;
        }
        catch(Exception ex)
        {
            throw ex;
        }
        return strResult;
    }
};