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    C# OleDbDataReader快速数据读取方式(3种)

    栏目:代码类 时间:2019-12-12 12:08

    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();
        }