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();    }  }}