根据我对SelectMany文档的理解,可以使用它来生成一个1-多关系的(扁平的)序列。
我有以下课程
public class Customer
{
public int Id { get; set; }
public string Name { get; set; }
}
class Order
{
public int Id { get; set; }
public int CustomerId { get; set; }
public string Description { get; set; }
}
然后尝试使用查询表达式语法来使用它们,如下所示
var customers = new Customer[]
{
new Customer() { Id=1, Name ="A"},
new Customer() { Id=2, Name ="B"},
new Customer() { Id=3, Name ="C"}
};
var orders = new Order[]
{
new Order { Id=1, CustomerId=1, Description="Order 1"},
new Order { Id=2, CustomerId=1, Description="Order 2"},
new Order { Id=3, CustomerId=1, Description="Order 3"},
new Order { Id=4, CustomerId=1, Description="Order 4"},
new Order { Id=5, CustomerId=2, Description="Order 5"},
new Order { Id=6, CustomerId=2, Description="Order 6"},
new Order { Id=7, CustomerId=3, Description="Order 7"},
new Order { Id=8, CustomerId=3, Description="Order 8"},
new Order { Id=9, CustomerId=3, Description="Order 9"}
};
var customerOrders = from c in customers
from o in orders
where o.CustomerId == c.Id
select new
{
CustomerId = c.Id
, OrderDescription = o.Description
};
foreach (var item in customerOrders)
Console.WriteLine(item.CustomerId + ": " + item.OrderDescription);
这给了我需要的东西。
1: Order 1
1: Order 2
1: Order 3
1: Order 4
2: Order 5
2: Order 6
3: Order 7
3: Order 8
3: Order 9
我假设这意味着在不使用查询表达式语法时使用SelectMany方法?
无论哪种方式,我都在尝试使用SelectMany。因此,即使我上面的查询不能转换为SelectMany,考虑到两个类和模拟数据,有人能为我提供一个使用SelectMany的linq查询吗?
https://stackoverflow.com/questions/5018361
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