SqlConnection conn = new SqlConnection();
            conn.ConnectionString = "server=LUKE\\SQLEXPRESS;uid=sa;pwd=sa;database=luke";
            conn.Open();
            DataTable dt = new DataTable("resouce");
            dt.Clear();
            SqlDataAdapter adp = new SqlDataAdapter("select * from text1", conn);
            adp.Fill(dt);
            dataGridView1.DataSource = dt.DefaultView;
这段代码是连接数据库，并显示数据的，我想把它写成类，然后调用，应该怎么做

public class BaseConnectionSql//这是一个连接数据库的基类，只需要其他类继承这个基类就OK,派生类只需要调用基类的属性就OK  
{
        protected string ConnectionString//封装属性
        {
            get
            {
                return System.Configuration.ConfigurationManager.ConnectionStrings["connectionstring"].ToString();//这里需要在web.config中配置后再用connectionstring
            }
        }
}
//配置中只需要这样添加就行
 <connectionStrings>      
      <add name="connectionstring" connectionString="server=.;database=luke;uid=sa;pwd=sa" />//这里的connectionstring就是基类中的connectionstring
 </connectionStrings>

建议你去百度收一下sqlHelper类中的封装