Share an example of ASP.NET database operation class

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;
namespace Mysqlserver
{
  /// <summary>
  /// SqlServerDataBase 的摘要说明
  /// </summary>
  public class SqlServerDataBase
  {
    private string strError = null;
    private int intCount = 0;
    public SqlServerDataBase()
    {
      //
      // TODO: 在此处添加构造函数逻辑
      //
    }
    /// <summary>
    /// 公开方法DBConn，返回数据库连接
    /// </summary>
    /// <returns></returns>
    public SqlConnection DBconn()
    {
      string strConn = "Server=(local);Database=GlobalMeetings;Uid=sa;pwd=";
      try
      {
        return new SqlConnection(strConn);
      }
      catch (Exception)
      {
        return null;
      }
    }
    /// <summary>
    /// 公开属性ErrorMessage，返回错误信息
    /// </summary>
    public string ErrorMessage
    {
      get
      {
        return strError;
      }
    }
    /// <summary>
    /// 根据查询语句从数据库检索数据
    /// </summary>
    /// <param name="strSelect">查询语句</param>
    /// <param name="SqlConn">数据库连接</param>
    /// <returns>有数据则返回DataSet对象，否则返回null</returns>
    public DataSet Select(string SelectString, SqlConnection sqlConn)
    {
      strError = "";
      SqlConnection conn;
      if (sqlConn == null)
      {
        conn = DBconn();
      }
      else
      {
        conn = sqlConn;
      }
      try
      {
        //若数据库连接的当前状态是关闭的，则打开连接
        if (conn.State == ConnectionState.Closed)
        {
          conn.Open();
        }
        SqlDataAdapter mySqlDataAdapter = new SqlDataAdapter();
        SqlCommand selectCommand = new SqlCommand(SelectString, conn);
        selectCommand.CommandType = CommandType.Text;
        mySqlDataAdapter.SelectCommand = selectCommand;
        DataSet myDS = new DataSet();
        mySqlDataAdapter.Fill(myDS);
        return myDS;
      }
      catch (Exception e)
      {
        strError = "数据检索失败：" + e.Message;
        return null;
      }
      finally
      {
        if (conn.State != ConnectionState.Closed)
        {
          conn.Close();
        }
      }
    }
    /// <summary>
    /// 更新数据库
    /// </summary>
    /// <param name="UpdateString">Update Sql语句</param>
    /// <param name="SqlConn">数据库连接</param>
    /// <returns>更新成功返回true</returns>
    public bool Update(string UpdateString, SqlConnection SqlConn)
    {
      return udiDataBase(UpdateString, SqlConn);
    }
    /// <summary>
    /// 从数据库中删除数据
    /// </summary>
    /// <param name="DeleteString">Delete Sql语句</param>
    /// <param name="SqlConn">数据库连接</param>
    /// <returns>删除成功返回true</returns>
    public bool Delete(string DeleteString, SqlConnection SqlConn)
    {
      return udiDataBase(DeleteString, SqlConn);
    }
    /// <summary>
    /// 把数据插入数据库
    /// </summary>
    /// <param name="InsertString">Insert Sql语句</param>
    /// <param name="SqlConn">数据库连接</param>
    /// <returns>插入成功返回true</returns>
    public bool Insert(string InsertString, SqlConnection SqlConn)
    {
      return udiDataBase(InsertString, SqlConn);
    }
    /// <summary>
    /// 根据Sql语句更新数据库
    /// </summary>
    /// <param name="UDIString">更新语句</param>
    /// <param name="SqlConn">数据库连接</param>
    /// <returns>更新成功则返回true</returns>
    public bool udiDataBase(string UDIString, SqlConnection SqlConn)
    {
      strError = "";
      SqlConnection conn;
      if (SqlConn == null)
      {
        conn = DBconn();
      }
      else
      {
        conn = SqlConn;
      }
      try
      {
        if (conn.State == ConnectionState.Closed)
        {
          conn.Open();
        }
        SqlCommand cmd = new SqlCommand(UDIString, conn);
        cmd.CommandType = CommandType.Text;
        intCount = cmd.ExecuteNonQuery();
        return !(intCount < 1);
      }
      catch (Exception e)
      {
        strError = "更新数据库失败：" + e.Message;
        return false;
      }
      finally
      {
        if (conn.State != ConnectionState.Closed)
        {
          conn.Close();
        }
      }
    }
  }
}