c# - LINQ左连接怎么写

Question

 var query = from r in db.Resource
                    join c in db.ResourceProjectedCapacity on r.ID equals c.ResourceID into ps
                    from c in ps.DefaultIfEmpty(null)
                    join p in db.Project on c.ProjectID equals p.ID
                    select new
                    {
                        Capacity = c,
                        Resource = r,
                        Project = p
                    };

我有这个 linq 查询，但它只返回在 ResourceProjectedCapacity 表上有匹配行的资源。我如何获取所有资源，如果它们没有匹配的记录，Capacity 对象为空？

Answer 1

from i in db.Resource
let c = db.ResourceProjectedCapacity.Where(cc => i.id == cc.ResourceID).FirstOrDefault()
let p = db.Project.Where(pp => c.ProjectID == pp.ID).FirstOrDefault() 
select new
{
  Capacity = C,
 Resource = i,
 Project = p
 }

试试上面的代码