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关于c＃：如何使用LINQ to SQL执行CROSS JOIN？

2023-04-14 23:30:00

How do you perform a CROSS JOIN with LINQ to SQL?

如何使用LINQ to SQL执行CROSS JOIN？

交叉联接只是两组的笛卡尔乘积。没有显式的join运算符。

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var combo = from p in people
from c in cars
select new
{
p.Name,
c.Make,
c.Model,
c.Colour
};

linq扩展方法也是如此：

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根据史蒂夫的回答，最简单的表达是这样的：

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var combo = from Person in people
from Car in cars
select new {Person, Car};

Tuple是笛卡尔积的好类型：

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public static IEnumerable<Tuple<T1, T2>> CrossJoin<T1, T2>(IEnumerable<T1> sequence1, IEnumerable<T2> sequence2)
{
return sequence1.SelectMany(t1 => sequence2.Select(t2 => Tuple.Create(t1, t2)));
}

扩展方式：

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public static IEnumerable<Tuple<T1, T2>> CrossJoin<T1, T2>(this IEnumerable<T1> sequence1, IEnumerable<T2> sequence2)
{
return sequence1.SelectMany(t1 => sequence2.Select(t2 => Tuple.Create(t1, t2)));
}

并使用像：