OleDbDataReader快速数据读取方式

Posted 2020-08-24 DullFish

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();
        }

View Code

循环50次结果，即50*105945：

100次循环结果:，即100*105945：