C# OleDbDataReader快速数据读取方式(3种)

查询得到OleDbDataReader后，有三种方式支持数据读取，如下：

//方法一**速度中等
OleDbDataReader reader = command.ExecuteReader();
while (reader.Read())
{
  var t1 = reader[0]; 
}

//方法二**速度最慢
OleDbDataReader reader = command.ExecuteReader();
while (reader.Read())
{
  var t1 = reader["字段名"]; 
}

//方法三**速度最快
OleDbDataReader reader = command.ExecuteReader();
while (reader.Read())
{
  var t1 = reader.GetValue(0); 
}

关于速度的描述，下面我们来简单验证一下。

有一个数据库，数据库中的表TEST有105945行数据，设计一个循环读取来测试他们的读取速度。

测试源码如下：

static void Main(string[] args)
    {
      string connstr = string.Format("Provider=Microsoft.Jet.OLEDB.4.0 ;Data Source={0};", "F:\\2.mdb");
      string s1 = "ID";
      string s2 = "探测号";
      string s3 = "X";
      string s4 = "Y";
      string s5 = "H";
      string sql = string.Format("SELECT {0},{1},{2},{3},{4} FROM 管点表", s1, s2, s3, s4, s5);
      TimeSpan time1 = new TimeSpan();
      TimeSpan time2 = new TimeSpan();
      TimeSpan time3 = new TimeSpan();

      int count = 50;

      //数据库中查询的表有105945行
      for (int i = 0; i < count; i++)
      {
        using (OleDbConnection conn = new OleDbConnection(connstr))
        {
          #region
          conn.Open();
          OleDbCommand command = conn.CreateCommand();
          command.CommandText = sql;
          OleDbDataReader reader = command.ExecuteReader();
          DateTime now = DateTime.Now;
          while (reader.Read())
          {
            var t1 = reader[0]; var t2 = reader[1]; var t3 = reader[2]; var t4 = reader[3]; var t5 = reader[4];
          }
          time1 = time1 + (DateTime.Now - now);
          #endregion
        }
      }
      for (int i = 0; i < count; i++)
      {
        using (OleDbConnection conn = new OleDbConnection(connstr))
        {
          #region
          conn.Open();
          
          OleDbCommand command2 = conn.CreateCommand();
          command2.CommandText = sql;
          OleDbDataReader reader = command2.ExecuteReader();
          DateTime now = DateTime.Now;
          while (reader.Read())
          {
            var t1 = reader[s1]; var t2 = reader[s2]; var t3 = reader[s3]; var t4 = reader[s4]; var t5 = reader[s5];
          }
          time2 = time2 + (DateTime.Now - now);
          #endregion
        }
      }
      for (int i = 0; i < count; i++)
      {
        using (OleDbConnection conn = new OleDbConnection(connstr))
        {
          #region
          conn.Open();

          OleDbCommand command3 = conn.CreateCommand();
          command3.CommandText = sql;
          OleDbDataReader reader = command3.ExecuteReader();
          DateTime now = DateTime.Now;
          while (reader.Read())
          {
            var t1 = reader.GetValue(0); var t2 = reader.GetValue(1); var t3 = reader.GetValue(2); var t4 = reader.GetValue(3); var t5 = reader.GetValue(4);
          }
          time3 = time3 + (DateTime.Now - now);
          #endregion
        }
      }
      Console.WriteLine(string.Format("方法一：\r\n耗时：{0}s", time1.TotalSeconds));
      Console.WriteLine(string.Format("方法二：\r\n耗时：{0}s", time2.TotalSeconds));
      Console.WriteLine(string.Format("方法三：\r\n耗时：{0}s", time3.TotalSeconds)); 
      Console.ReadKey();
    }

循环50次结果，即50*105945：

100次循环结果:，即100*105945：

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