如何在Linq中执行左外连接?
本文关键字:连接 执行 Linq | 更新日期: 2023-09-27 18:14:43
我是Linq的新手,我需要将此查询转换为DocumentStores和Orders之间的左外连接,因为并非所有文档都与订单相关:
var documents=(from d in _dataContextOrders .DocumentStores
join o in _dataContextOrders.Orders on d.OrderID equals o.ID
join t in _dataContextOrders .DocumentTypes on d.DocumentType equals t.DocTypeID
select new
{
d.ID,
o.PORef ,
t.DocTypeDescription,
d.Name,
d.ContentType
}).ToList();
我如何做到这一点?
from a in dataContext.<tableA>
join _b in dataContext.<tableB> on a.id equals _b.aid into _b
from b in _b.DefaultIfEmpty()
select <whatyouwanttoselect>
b将为空,如果id的连接失败