c# – 如何在我们在sql中使用的linq中使用左连接?
发布时间:2020-12-15 22:31:44 所属栏目:百科 来源:网络整理
导读:如何在 Linq中使用Left join来编写SQL查询? select p.Name,p.Family,E.EmployTypecode,E.employtypeName,E.EmplytyppeTye from personnel as pleft join Employee as E on E.EmployTypecode = p.EmployTypecode 解决方法 使用Join关键字而不是Left join,必
如何在
Linq中使用Left join来编写SQL查询?
select p.Name,p.Family,E.EmployTypecode,E.employtypeName,E.EmplytyppeTye from personnel as p left join Employee as E on E.EmployTypecode = p.EmployTypecode 解决方法
使用Join关键字而不是Left join,必须使用“INTO”关键字和“DefaultIfEmpty()”方法,因为右表返回null值.
var query = from p in personnel join e in Employee on p.EmployTypecode equals e.EmployTypecode into t from nt in t.DefaultIfEmpty() orderby p.Name select new { p.Name,EmployTypecode=(int?)nt.EmployTypecode,// To handle null value if Employtypecode is specified as not null in Employee table. nt.employtypeName,nt.EmplytyppeTye }.ToList(); (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |