假设有A,B两个表. 表A记录如下: aID aNum a20050111 a20050112 a20050113 a20050114 a20050115 表B记录如下: bID bName -------------------------------------------- .left join sql语句如下: select * from A left join B on A.aID = B.bID 结果如下: aID aNum bID bName a20050111 a20050112
var query1 = from r in _residentRepository.GetAll() join i in _inLogRepository.GetAll() on r.Id equals i.ResidentId into tmp_ir from ir in tmp_ir.DefaultIfEmpty() || r.Id == select new { resId = r.Id, Id = ir.Id }; var sum1 = query1.Count(); 结果:左连接 一
Left Join / Right Join /inner join相关 关于左连接和右连接总结性的一句话: 左连接where只影向右表,右连接where只影响左表. Left Join select * from tbl1 Left Join tbl2 where tbl1.ID = tbl2.ID 左连接后的检索结果是显示tbl1的所有数据和tbl2中满足where 条件的数据. 简言之 Left Join影响到的是右边的表 Right Join select * from tbl1 Rig