Web部件访问SQL数据库

 最近一段时间在摸索web部件的开发技术，前两天做了个在WEB部件中连接SQL数据库的小例子，刚开始无论如何都无法连接到数据库，总是出现以下的异常信息：
Request for the permission of type System.Data.SqlClientPermission,System.Data,Version=1.0.5000.0,Culture=neutral,PublicKeyToken=b77a5c561934e089 failed.
   
       后来在一个有关SPS的英文论坛中找到了解决的方法：
      
       打开在SPS服务器的虚拟目录中web.config文件，在该文件中有个节点：
<trustLevel name="WSS_Medium" policyFile="C:Program Files\Common Files\Microsoft Shared\Web Server Extensions\60\config\wss_minimaltrust.config"/>，
该节点记录了wss_minimaltrust.config文件所在的目录，根据这个目录找到该文件。

       然后在wss_minimaltrust.config文件的<SecurityClass>节点中加入子节点：
<SecurityClass Name="SqlClientPermission" Description="System.Data.SqlClient.SqlClientPermission, System.Data, Version=1.0.5000.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>，
      
       再在<PermissionSet>节点中加入子节点：
<IPermissionSet class="SqlClientPermission" version="1" Unrestricted="true"/>

       下面是我写的一个简单的访问数据库的例子，该例子从Goods数据库中的GoodsInformation表中查询有关Goods的信息，
然后把查询到的信息以表格的形式显示在Web部件中：

protected override void RenderWebPart(HtmlTextWriter output)
{
        string dataSource = "Data Source = 192.168.0.200;";       
        string initialCatalog = "Initial Catalog = Goods;";
        string userId = "User ID = sa;";
        string password = "Password =;";
        string connectionStr = dataSource + initialCatalog + userId + password;

        SqlConnection goodsConnection = new SqlConnection(connectionStr);
        SqlDataAdapter goodsAdp = null;
        DataSet goodsDataSet = null;

        try
        {
                goodsConnection.Open();
                string sqlSelectStr = "select * from GoodsInformation";
                goodsAdp = new SqlDataAdapter(sqlSelectStr,goodsConnection);
                goodsDataSet = new DataSet();
                goodsAdp.Fill(goodsDataSet);
                goodsConnection.Close();
        }
        catch(Exception ex)
        {
                output.Write(ex.Message);
                return;
        }
        finally
        {
                goodsConnection = null;       
                goodsAdp = null;
        }
                       
        int rowCount = goodsDataSet.Tables[0].Rows.Count;
        int tableHeight = rowCount * 25;
        output.Write("<TABLE id=\"NewTable\" style=\"Z-INDEX: 101; LEFT: 56px; WIDTH: 600px; TOP: 136px; HEIGHT: "+ tableHeight + "px\"" +
                                "cellSpacing=\"1\" cellPadding=\"1\" width=\"550\" border=\"0\">");
                       
        for(int rowIndex=0; rowIndex<rowCount; rowIndex++)
        {
                string name = goodsDataSet.Tables[0].Rows[rowIndex].ItemArray[0].ToString();
                string price = goodsDataSet.Tables[0].Rows[rowIndex].ItemArray[1].ToString();
                string manufacturer = goodsDataSet.Tables[0].Rows[rowIndex].ItemArray[2].ToString();

                System.Web.UI.WebControls.HyperLink hlinkManufacturer = new HyperLink();
                hlinkManufacturer.Text = manufacturer;
                hlinkManufacturer.NavigateUrl = "http://www.google.com";
                hlinkManufacturer.Target = "_blank";

                output.Write("<TR bgColor=#dcdcdc>");
                output.Write("<TD style=\"WIDTH: 85px\"><FONT face=\"MS UI Gothic\">" + name + "</FONT></TD>");                               
                output.Write("<TD style=\"WIDTH: 100px\"><FONT face=\"MS UI Gothic\">" + price + "</FONT></TD>");

                output.Write("<TD><FONT face=\"MS UI Gothic\">");
                hlinkManufacturer.RenderControl(output);
                output.Write("</FONT></TD>");

                output.Write("</TR>");
        }
                       
        output.Write("</TABLE>");
        goodsDataSet = null;
}