记录一个简单的DBHelper类吧，用的时候在上来拿！

/// <summary>
    /// 数据库连接工具类
    /// </summary>
    public class DBHelper
    {
        string constr = "Data Source=.;Initial Catalog=schoolDB;Integrated Security=True";
        private SqlConnection conn;

        //数据库连接Connection对象
        public SqlConnection getConnection() { 
            if(conn==null){
                conn = new SqlConnection(constr);
            }
            return conn;
        }


        //打开连接
        public void OpenConnection() { 
            if(conn.State==ConnectionState.Closed){
                conn.Open();
            }else if(conn.State==ConnectionState.Broken){
                conn.Close();
                conn.Open();
            }
        }

        //关闭连接
        public void CloseConnection() { 
            if(conn.State==ConnectionState.Open||conn.State==ConnectionState.Broken){
                conn.Close();
            }
        }
    }