如何执行与LINQ to SQL的CROSS JOIN？

如何执行与LINQ to SQL的CROSS JOIN？

Answer 1

交叉连接就是两组笛卡尔积。 没有明确的join运算符。

 var combo =从p在人
            从C在汽车
            select新的
             {
                 p.Name，
                 c.Make，
                 c.Model，
                 c.Colour
             };

Answer 2

linq扩展方法也一样：

 var names = new string[] { "Ana", "Raz", "John" }; var numbers = new int[] { 1, 2, 3 }; var newList=names.SelectMany( x => numbers, (y, z) => { return y + z + " test "; }); foreach (var item in newList) { Console.WriteLine(item); } 

Answer 3

根据史蒂夫的回答，最简单的expression就是：

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

Answer 4

Tuple是笛卡尔积的一个很好的types：

 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))); } 

Answer 5

扩展方法：

 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：

 vals1.CrossJoin(vals2)