实体框架和交叉/外部应用 [英] Entity Framework and CROSS/OUTER APPLY

问题描述

我想为Entity Framework查询创建一些测试用例，以确保生成包含CROSS APPLY或OUTER APPLY运算符的SQL命令.

I want to create some test cases for Entity Framework queries that surely generate SQL commands that contain CROSS APPLY or OUTER APPLY operators.

有人能显示出出现这类SQL查询的典型情况吗?

Could someone show typical scenarios where these kind of SQL queries appear?

推荐答案

在LINQ 2 SQL中，这总是导致APPLY:

In LINQ 2 SQL this always results in an APPLY:

from t1 in tab1
from t2 in tab2.Where(t2 => t2.SomeCol == t1.SomeCol).Take(1)
select new { t1, t2 }

在EF中，这可能会失败，或者还会导致APPLY(我不知道是哪个).这是一个关联联接，在SQL端需要一个APPLY.

In EF this will either fail, or also result in an APPLY (I don't know which one). This is a correlated join which requires an APPLY on the SQL side.

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