【IT168技术】关于ado.net entity framework 性能比较网上也有很多，这里我只是初步的介绍下ado.net entity framework使用不同的方法查询数据的不同性能
第一部分：重复查询单个实体
第一种：Linq To Entitiess
代码如下：
static void Main(string[] args)
{
DateTime time1;
DateTime time2;
time1 = DateTime.Now;
NorthwindEntities context = new NorthwindEntities();
for (int i = 0; i < 1000; i++)
{
var data = (from c in context.Customers where c.CustomerID == "ALFKI" select c).FirstOrDefault();
string addr = data.Address;
}
time2 = DateTime.Now;
Console.WriteLine((time2-time1).ToString());
}
{
DateTime time1;
DateTime time2;
time1 = DateTime.Now;
NorthwindEntities context = new NorthwindEntities();
for (int i = 0; i < 1000; i++)
{
var data = (from c in context.Customers where c.CustomerID == "ALFKI" select c).FirstOrDefault();
string addr = data.Address;
}
time2 = DateTime.Now;
Console.WriteLine((time2-time1).ToString());
}
查询使用时间为6.2秒左右
第二种：使用Entity SQL
static void Main(string[] args)
{
DateTime time1;
DateTime time2;
time1 = DateTime.Now;
NorthwindEntities context = new NorthwindEntities();
for (int i = 0; i < 1000; i++)
{
var data = context.Customers.Where("it.CustomerID=@Id", new System.Data.Objects.ObjectParameter("Id", "ALFKI")).FirstOrDefault();
string addr = data.Address;
}
time2 = DateTime.Now;
Console.WriteLine((time2-time1).ToString());
}
{
DateTime time1;
DateTime time2;
time1 = DateTime.Now;
NorthwindEntities context = new NorthwindEntities();
for (int i = 0; i < 1000; i++)
{
var data = context.Customers.Where("it.CustomerID=@Id", new System.Data.Objects.ObjectParameter("Id", "ALFKI")).FirstOrDefault();
string addr = data.Address;
}
time2 = DateTime.Now;
Console.WriteLine((time2-time1).ToString());
}
查询使用时间为6.2秒左右
第三种：使用EntityKey 来查询
static void Main(string[] args)
{
DateTime time1;
DateTime time2;
time1 = DateTime.Now;
NorthwindEntities context = new NorthwindEntities();
for (int i = 0; i < 1000; i++)
{
var data = context.GetObjectByKey(new System.Data.EntityKey("NorthwindEntities.Customers", "CustomerID", "ALFKI")) as Customers;
string addr = data.Address;
}
time2 = DateTime.Now;
Console.WriteLine((time2-time1).ToString());
}
{
DateTime time1;
DateTime time2;
time1 = DateTime.Now;
NorthwindEntities context = new NorthwindEntities();
for (int i = 0; i < 1000; i++)
{
var data = context.GetObjectByKey(new System.Data.EntityKey("NorthwindEntities.Customers", "CustomerID", "ALFKI")) as Customers;
string addr = data.Address;
}
time2 = DateTime.Now;
Console.WriteLine((time2-time1).ToString());
}
查询使用时间为1秒，没错是一秒
总结：
前两种方法查询所使用的时间都差不多为6.2秒，时间比较长，但是使用第三种方法查询数据仅仅使用了1秒，为什么会相差那么多，区别在于前两种方法每次查询都要从数据库中查找，1000次查询每次的查询时间都一样，但是第三种方法只有第一次是从数据库中查数据，后面的999次都是在context通过主键直接取数据，速度当然会快很多啦，EF4.0之前的实体当含有外键引用时是自动生成对象引用的，而EF4.0现在多了一个外键ID，这样我们可以很方便的通过外键来查询数据
