ADO--数据访问技术

static void Main(string[] args)
        {
            //创建连接字符串
            string constr = "Data Source=PENGYOUQIANG-PC;Initial Catalog=lianlian;Integrated Security=True";
            //创建连接对象
            using (SqlConnection con = new SqlConnection(constr))
            { 
                //编写执行的SQL语句
                string Sql = "select * from lianxi";
                //执行SQL语句
                using(SqlCommand comm=new SqlCommand(Sql,con))
                {
                    //打开连接
                    con.Open();
                    using (SqlDataReader reader=comm.ExecuteReader())
                    {
                        //判断表中是否有数据
                        if (reader.HasRows)
                        {
                            //一行一行读取数据
                            while(reader.Read())
                            {
                                Console.Write(reader.GetInt32(0)+"    ");
                                Console.Write(reader.GetString(1) + "    ");
                                Console.Write(reader.GetString(2) + "    ");
                                Console.Write(reader.GetString(3) + "    ");
                                //用GetXxxx方法来获取值，如果为NULL会报异常，此时需要手写代码来判断
                                //Console.WriteLine(reader.IsDBNull(4) ? "NULL" : reader.GetInt32(4));
                                Console.Write(reader.GetInt32(4));
                                Console.WriteLine();
                            }
                            Console.ReadKey();
                        }
                    }
                }
            }
        }