Linq 三表 left join 的实现

目的实现:

　　　　select id,name,jname,cname from userinfo u left join job j on u.job=j.jid left join city c on u.city=c.cid  多表left join

代码如下：

var list = (from u in dc.userinfos
                        join j in dc.jobs on u.job equals j.jid into j_join
                        from x in j_join.DefaultIfEmpty()
                        join c in dc.cities on u.city equals c.cid into c_join
                        from v in c_join.DefaultIfEmpty()
                        select new
                        {
                            id=u.id,
                            name=u.name,
                            jname=x.jname,
                            cname=v.cname,
                           /*u1=u,x1=x,v1=v*///不要用对象的方式 因为对象可能为null那么对象.属性就会抛异常
                        }).ToList();