IQueryable与IEnumberable的区别有哪些



一、IEnumerable接口

公开枚举器，该枚举器支持在指定类型的集合上进行简单迭代。也就是说：实现了此接口的object，就可以直接使用foreach遍历此object

二、IQueryable 接口

它继承 IEnumerable 接口，而因为.net版本加入Linq和IQueryable后，使得IEnumerable不再那么单调，变得更加强大和丰富。

三、IQueryable与IEnumberable的区别

1、IEnumerable<T> 泛型类在调用自己的SKip 和 Take 等扩展方法之前数据就已经加载在本地内存里了

2、IQueryable<T> 是将Skip ,take 这些方法表达式翻译成T-SQL语句之后再向SQL服务器发送命令，它并不是把所有数据都加载到内存里来才进行条件过滤。

四、IQueryable与IEnumberable的实例说明一

1、IEnumerable实例

var set3 = (from c in db.cms_certificateDetails select c).OrderByDescending(c => c.id).AsEnumerable()
 .Skip(150).Take(10);
 foreach (var cmsCertificateDetailse in set3)
 {
 Console.WriteLine(cmsCertificateDetailse.czry + ";" + cmsCertificateDetailse.kddh + "\\r\\n");//打印结果
}
           

生成的SQL 语句

SELECT 
[Extent1].[id] AS [id], 
[Extent1].[kddh] AS [kddh], 
[Extent1].[czry] AS [czry], 
[Extent1].[yjnr] AS [yjnr], 
[Extent1].[tjTime] AS [tjTime], 
[Extent1].[bz] AS [bz], 
[Extent1].[forId] AS [forId]
FROM [dbo].[cms_certificateDetails] AS [Extent1]
ORDER BY [Extent1].[id] DESC
           

2、IQueryable实例

var set4 = (from c in db.cms_certificateDetails select c).OrderByDescending(c => c.id).AsQueryable()
 .Skip(150).Take(10);
 foreach (var cmsCertificateDetailse in set4)
 {
 Console.WriteLine(cmsCertificateDetailse.czry + ";" + cmsCertificateDetailse.kddh + "\\r\\n");//打印结果
}
           

生成的SQL语句

SELECT TOP (10) 
[Extent1].[id] AS [id], 
[Extent1].[kddh] AS [kddh], 
[Extent1].[czry] AS [czry], 
[Extent1].[yjnr] AS [yjnr], 
[Extent1].[tjTime] AS [tjTime], 
[Extent1].[bz] AS [bz], 
[Extent1].[forId] AS [forId]
FROM ( SELECT [Extent1].[id] AS [id], [Extent1].[kddh] AS [kddh], [Extent1].[czry] AS [czry], [Extent1].[yjnr] AS [yjnr], [Extent1].[tjTime] AS [tjTime], [Extent1].[bz] AS [bz], [Extent1].[forId] AS [forId], row_number() OVER (ORDER BY [Extent1].[id] DESC) AS [row_number]
    FROM [dbo].[cms_certificateDetails] AS [Extent1]
) AS [Extent1]
WHERE [Extent1].[row_number] > 150
ORDER BY [Extent1].[id] DESC
           

文章转载自：   IQueryable与IEnumberable的区别   http://www.studyofnet.com/news/730.html