C#使用SQL DataReader访问数据的优点和实例

using System;
using System.Data.SqlClient;
namespace DataReaderDemo
{
  class Program
  {
    static void Main(string[] args)
    {
      string constr = "Server = .; user=name;pwd=mima;database=mysql";
      SqlConnection myCon = new SqlConnection(constr);
      try
      {
        myCon.Open();
        string sql = "select * from mytable01 ";
        SqlCommand mycom = new SqlCommand(sql, myCon);
        //声明DataReader
        SqlDataReader mydr;
        mydr = mycom.ExecuteReader();
        if (mydr.HasRows)   
        {
          Console.WriteLine("mytable01中存在数据");
        }
        else
        {
          Console.WriteLine("mytable01中不存在任何数据");
        }
        //----------------方法----------------------
        Console.WriteLine("第一列的数据类型"+mydr.GetDataTypeName(0));
        Console.WriteLine("获取对应列的名称:(第一列)"+mydr.GetName(0));
        string mystr = "age";  //直接写会报异常，需要有个转换的过程
        Console.WriteLine(mydr.GetOrdinal(mystr));
        /* 此时将上面的15行的str，换为
         *  string sql = "select * from mytable01 where id=1";
        if (mydr.Read())
        {
          Console.WriteLine("取得指定字段的数据：" + mydr.GetValue(0));
        }
         */
        /*将15行的 str更改为：
         * string sql = "select * from mytable01 where gender='男'";
        object[] myobj = new object[mydr.FieldCount];
        while(myde.Read()){
          mydr.GetValues(myobj);
          foreach (object item in myobj)
          {
            Console.Write(item + "\t");
            Console.WriteLine();
          }
         } 
        */
        //访问DataReader 对象时使用索引要比字段名称快很多
        while (mydr.Read())
        {
          Console.WriteLine(mydr[0].ToString()+",");
          Console.WriteLine(mydr[1].ToString() + ",");
          Console.WriteLine(mydr["gender"].ToString());
        }
        //----------------属性----------------------
        Console.WriteLine("表中有几个字段:"+mydr.FieldCount);
        Console.WriteLine("是否关闭："+mydr.IsClosed);
        mydr.Close();
        Console.WriteLine("是否关闭：" + mydr.IsClosed);
      }
      catch(Exception ex)
      {
        Console.WriteLine(ex.Message.ToString());
      }
      finally
      {
        myCon.Close();
      }
      Console.Read();
    }
  }
}