如何在Entity Framework Linq中左键连接2个子选择？

Question

如何使用Entity Framework在c＃中编写此查询？

Select Id, Name, DeliveryAdress, InvoiceAdress from Company 
left join (Select Address.CompanyId as CompanyId, Street + ' ' + ZipCode + '     ' + City as DeliveryAdress from Address 
join AddressType on AddressType.AddressTypeId = Address.AddressTypeId
where AddressType.Name = 'Delivery') sub1 on sub1.CompanyId = Company.Id
left join (Select Address.CompanyId as CompanyId, Street + ' ' + ZipCode + ' ' + City as InvoiceAdress from Address 
join AddressType on AddressType.AddressTypeId = Address.AddressTypeId
where AddressType.Name = 'Invoice') sub2 on sub2.CompanyId = Company.Id

事实上，我有3个表：公司，地址和地址类型，在此查询中，我必须从公司中选择ID和名称，并通过typename选择2个地址......

Answer 1

首先通过加入地址和地址类型获取DeliveryAddresses列表

var deliveryaddresses=
from addr in db.Addresses join (addrtype in    
db.AddressTypes.Where(at=>at.Name=="Delivery")) on addr.AddressTypeId equals 
addrtype.AddressTypeId select new {CompanyId=addr.CompanyId,
DeliveryAddress= addr.Street + " " + ZipCode + " " + City}

下一步通过加入地址和地址类型获取发票地址列表

var invoiceaddresses=
from addr in db.Addresses join (addrtype in    
db.AddressTypes.Where(at=>at.Name=="Invoice")) on addr.AddressTypeId equals 
addrtype.AddressTypeId select new {CompanyId=addr.CompanyId,
InvoiceAddress= addr.Street + " " + ZipCode + " " + City}

然后在DeliveryAddresses和invoiceAddresses上执行Left Outer Join

var deliveryandinvoiceaddresses=from da in deliveryaddresses join ia in    
invoiceaddresses on da.CompanyId equals ia.companyId into addrgroup from ag     
in addrgroup.DefaultIfEmpty() select new   
{CompanyId=da.CompanyId,DeliveryAddress=da.DeliveryAddress,InvoiceAddress= 
(ag==null?string.Empty:ag.InvoiceAddress)}

最后在公司上执行左外连接以及交货和发票地址的外连接结果

var completelist=from c in db.companys join d in deliveryandinvoiceaddresses   
on c.Id equals d.CompanyId into compgroup from cg in 
companygroup.DefaultIfEmpty() select new {CompanyId=c.Id, 
Name=c.Name,DeliveryAddress=(cg==null?string.Empty:cg.DeliveryAddress), 
InvoiceAddress=(cg==null?string.Empty:cg.InvoiceAddress)}

希望它能解决问题。