数据访问的基本类

using System;
using System.Data;
using System.Data.SqlClient;

namespace Model
{
 /// <summary>
 /// 数据访问的基类
 /// </summary>
 public class DBase: IDisposable
 {
  SqlConnection cn;
  SqlCommand cmd;
  public DBase()
  {
   cn=new SqlConnection(System.Configuration.ConfigurationSettings.AppSettings["connnectionString"]);
   cn.Open();
   cmd=new SqlCommand();
   cmd.Connection=cn;
  }
  public void Fill(string sqlStr, DataTable dt)
  {
   SqlDataAdapter ada = new SqlDataAdapter();
   ada.SelectCommand = cmd;
   cmd.CommandText = sqlStr;
   ada.Fill(dt);
  }
  public void ExeNoRuturn(string sqlStr)
  {
   cmd.CommandText = sqlStr;
   cmd.ExecuteNonQuery();
  }
  public object ExeRuturnValue(string sqlStr)
  {
   cmd.CommandText = sqlStr;
   return cmd.ExecuteScalar();
  }
  #region IDisposable 成员
  public void Dispose()
  {
   cmd.Dispose();
   cn.Close();
   cn.Dispose();
  }
  #endregion
 }
}