ADO.NET常用五种对象

        static void Main(string[] args)
        {
            string conn_string = "Data Source=localhost;Initial Catalog=SQLtest;Integrated Security=True";

 using(SqlConnection connection = new SqlConnection(conn_string)){
            SqlCommand sqcm = new SqlCommand("SelectAll", connection);
            sqcm.CommandType = CommandType.StoredProcedure;
            SqlDataAdapter sqda = new SqlDataAdapter(sqcm);
            DataSet da = new DataSet();
            
            sqda.Fill(da);
         
            foreach (DataTable item in da.Tables )       //  学会使用DataSet.Tables对象
            {
                foreach (DataRow item2 in item.Rows)
                {
                    foreach (DataColumn  item3 in item.Columns)
                    {
                        Console.Write("{0}   {1}     {2}",item.TableName,item3.ColumnName,item2[item3]);
                    }
                    Console.WriteLine();
                }
            }
            Console.WriteLine();
            Console.WriteLine();
            DataTable dt = new DataTable();
            sqda.Fill(dt);
            foreach (DataRow item2 in dt.Rows)      //  学会使用DataRow对象
            {  
                foreach (DataColumn item3 in dt.Columns)     //  学会使用DataColumn对象
                {
                    Console.Write("{0}   {1} ",  item3.ColumnName, item2[item3]);
                }
                Console.WriteLine();
            }
            Console.ReadKey();
        }
             Connection.Close();
}

            SqlCommand sqcm = new SqlCommand("SelectAll", connection);  
            sqcm.CommandType = CommandType.StoredProcedure;  
            connection.Open();
            SqlDataReader reader = sqcm.ExecuteReader();    // SqlCommand.ExecuteReader方法返回一个DataReader变量
            // Call Read before accessing data.
            while (reader.Read())                       // 可以一直迭代读取的时候
            {
                ReadSingleRow(reader);                  // 就输出里面的内容
            }
            // Call Close when done reading.
            reader.Close();
          Connection.Close();