基于 null 进行选择

发布于 2024-11-05 23:26:51 字数 301 浏览 1 评论 0原文

我正在构建一个动态查询并在两个实体之间进行连接：正在构建的查询和一个表。

我：

var TheQuery = ...;

TheQuery = from x in TheQuery
           join c in MyDataContext.TheTable on
           x.ID equals c.ID
           where "there's no matching element in TheTable"
           select x

谢谢你的建议。

原文

I'm building a dynamic query and doing a join between 2 entities: the query being built and a table.

I have:

var TheQuery = ...;

TheQuery = from x in TheQuery
           join c in MyDataContext.TheTable on
           x.ID equals c.ID
           where "there's no matching element in TheTable"
           select x

Thanks for your suggestions.

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

断桥再见 2024-11-12 23:26:51

要使用 LINQ 进行左外连接，您必须使用 join .. into 和 DefaultIfEmpty()：

TheQuery = from x in TheQuery
           join c in MyDataContext.TheTable on x.ID equals c.ID into outer
           from o in outer.DefaultIfEmpty()
           where o == null
           select x

To do a Left outer join with LINQ you have to use join .. into and DefaultIfEmpty():

TheQuery = from x in TheQuery
           join c in MyDataContext.TheTable on x.ID equals c.ID into outer
           from o in outer.DefaultIfEmpty()
           where o == null
           select x

回复收藏 0 原文

~没有更多了~