This article won’t go into what these interfaces are, or the differences between them. For that, read this article for a good introduction.

本文将不讨论这些接口是什么或它们之间的区别。 为此，请阅读本文以获得良好的介绍。

Instead, I’ll show you an example of an Exception you can get from IQueryable but not from IEnumerable, for the exact same query.

相反，我将向您展示一个Exception的示例，您可以从IQueryable而不是IEnumerable那里获得完全相同的查询。

呼叫跳过(-x) (Calling Skip(-x))

Have a look at this code:

看一下这段代码：

IEnumerable<int> ids = GetIds();

IEnumerable<int> ids = GetIds();

ids.Skip(-4);

ids.Skip(-4);

This works fine.

这很好。

例外 (The Exception)

However, the following will throw an Exception:

但是，以下内容将引发Exception ：

IQueryable<int> ids = GetIds();

IQueryable<int> ids = GetIds();

ids.Skip(-4);

ids.Skip(-4);

错误讯息 (The Error Message)

The offset specified in a OFFSET clause may not be negative.

OFFSET子句中指定的偏移量不能为负。

为什么？ (Why?)

The reason for the error is because the IQueryable<int> creates the following SQL query:

错误的原因是因为IQueryable<int>创建以下SQL查询：

SELECT [p].[Id]FROM [Ids] AS [p]ORDER BY (SELECT 1)OFFSET @__p_0 ROWS

In SQL, offsetcan’t have a negative value.

在SQL中， offset不能为负值。