用lambda表达式写左联查询的示例

需要完成的查询逻辑:A表内联B表,B表左联C表,A表左联D表,并且 C表的TotalCount>23,D表的ClassHour>8,最后查出A表的Id,代码如下:

IQueryable<int> biz_AAA_IdQueryable = uow.Biz_AAA.GetAll()
                              .Join(uow.Biz_BBB.GetAll(), a => a.CertificateId, b => b.Id, (a, b) => new { a, b })
                              .GroupJoin(uow.Biz_CCC.GetAll(), o => o.b.IDNumber, c => c.IDNumber, (o, c) => new { o.a, o.b, c })
                              .SelectMany(cc => cc.c.DefaultIfEmpty(), (o, cc) => new { o.a, o.b, c = cc })
                              .GroupJoin(uow.Biz_DDD.GetAll(), o => o.a.Id, d => d.CertificateDelayApplyRecordId, (o, d) => new { o.a, o.b, o.c, d })
                              .SelectMany(dd => dd.d.DefaultIfEmpty(), (o, dd) => new { o.a, o.b, o.c, d = dd })
                              .Select(o => new
                              {
                                  CertificateDelayApplyRecordId = o.a.Id,
                                  CreateDate = o.a.CreateDate,
                                  OnLineClassHour = o.c == null ? 0 : o.c.TotalCount,
                                  OffLineClassHour = o.d == null ? 0 : o.d.ClassHour
                              })
                        .Where(o => o.OnLineClassHour > 23 && o.OffLineClassHour > 8)
                        .Select(o => o.CertificateDelayApplyRecordId);

希望写的东西,能够帮到别人,自己在网上找了很久,用别人的写法,生成的时候,总是报错,后面自己研究了下,发现这个写法是OK的,生成的sql语句是我想要的语句。

posted @ 2019-07-31 16:13  好记性不如烂笔头啊  阅读(737)  评论(0编辑  收藏  举报