C# 如何使用LINQ到SQL执行交叉连接?
如何使用LINQ到SQL执行交叉联接?交叉联接只是两个集合的笛卡尔乘积。它没有显式的联接运算符 var combo = from p in people from c in cars select new { p.Name, c.Make, c.Model, c.Colour }; var combo=人中的p 从c到汽车 选择新的 { p、 名字, c、 使, c、 模型, c、 颜色 };C# 如何使用LINQ到SQL执行交叉连接?,c#,linq,linq-to-sql,cross-join,C#,Linq,Linq To Sql,Cross Join,如何使用LINQ到SQL执行交叉联接?交叉联接只是两个集合的笛卡尔乘积。它没有显式的联接运算符 var combo = from p in people from c in cars select new { p.Name, c.Make, c.Model, c.Colour
根据Steve的回答,最简单的表达是:
var combo = from Person in people
from Car in cars
select new {Person, Car};
与
linq
扩展方法相同:
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);
}
对于笛卡尔乘积,
元组
是一种很好的类型:
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)));
}
公共静态IEnumerable交叉连接(IEnumerable sequence1,IEnumerable sequence2)
{
返回sequence1.SelectMany(t1=>sequence2.Select(t2=>Tuple.Create(t1,t2));
}
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)));
}
你是如何用lambda表示法从p到c从p再到车里的写的呢?
人。选择many(p=>cars,(p,c)=>new{…})
vals1.CrossJoin(vals2)