具有多个条件的 LINQ to EF 左连接

发布于 2024-08-20 01:09:47 字数 670 浏览 9 评论 0原文

我尝试使用 LINQ to EF 复制以下 SQL，但没有成功。

select * from Role
left join QueueAccess on Role.RoleId = QueueAccess.RoleId and queueId = 361

这是我尝试过的。

var myAccess = (from role in entity.Role.Include(p => p.QueueAccess)
join qa in entity.QueueAccess
on new { rID = role.RoleId, qID = queueId } equals new { rID = qa.RoleId, qID = qa.QueueId }
select role).ToList();

也尝试过这个。

var myAccess = entity.Role.Include(p => p.QueueAccess)
         .Where(x => x.QueueAccess.Any(a => a.QueueId == queueId)).ToList();

我继续只获取具有指定queueId的记录，但没有获取queueId为空的其他记录。

感谢您的帮助。

原文

I am trying to replicate the following SQL using LINQ to EF but with no luck.

select * from Role
left join QueueAccess on Role.RoleId = QueueAccess.RoleId and queueId = 361

Here's what I've tried.

var myAccess = (from role in entity.Role.Include(p => p.QueueAccess)
join qa in entity.QueueAccess
on new { rID = role.RoleId, qID = queueId } equals new { rID = qa.RoleId, qID = qa.QueueId }
select role).ToList();

Also tried this.

var myAccess = entity.Role.Include(p => p.QueueAccess)
         .Where(x => x.QueueAccess.Any(a => a.QueueId == queueId)).ToList();

I keep on getting only the record with the specified queueId but none of the other records where the queueId is null.

Thanks for your help.

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云巢 2024-08-27 01:09:47

在 LINQ to Entities 中使用 join 几乎总是错误的。相反，请执行以下操作：

var myAccess = (((ObjectQuery)from role in entity.Role
                              where role.QueueAccess.Any(a => a.QueueId == queueId)
                              select role).Include("QueueAccess")).ToList();

It's nearly always a mistake to use join in LINQ to Entities. Instead, do:

var myAccess = (((ObjectQuery)from role in entity.Role
                              where role.QueueAccess.Any(a => a.QueueId == queueId)
                              select role).Include("QueueAccess")).ToList();

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℉絮湮 2024-08-27 01:09:47

尝试这样的事情：

var access = from role in Role
             join oq in (from q in QueueAccess
                         where q.queueId = 361
                         select q) on role.RoleId equals queue.RoleId into oqs
             from queue in oqs.DefaultIfEmpty()
             select new { role.RoleId, queue.Property };

Try something like this:

var access = from role in Role
             join oq in (from q in QueueAccess
                         where q.queueId = 361
                         select q) on role.RoleId equals queue.RoleId into oqs
             from queue in oqs.DefaultIfEmpty()
             select new { role.RoleId, queue.Property };

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空宴 2024-08-27 01:09:47

类似的方法也有效，将条件放在 ON 中，而不是放在 WHERE 子句中。

join tbl3 in model.phone.Where(p => p.queue == 0  && p.phnkey == key) on x.key equals tbl3.y into a3
                            from phn in a3.DefaultIfEmpty()
                            where (phn.abc == 0 )

Something like this works too, puts the condition in the ON as oppose to the WHERE clause.

join tbl3 in model.phone.Where(p => p.queue == 0  && p.phnkey == key) on x.key equals tbl3.y into a3
                            from phn in a3.DefaultIfEmpty()
                            where (phn.abc == 0 )

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