Linq to sql 不断返回 null
我有以下 SQL 查询：
SELECT DISTINCT
Participant.BackgroundTrainingID,
Location.TrainingSite
FROM Registration, ProgramLocation, Participant, Program, Location
WHERE ProgramLocation.LocationID = Location.LocationID
AND ProgramLocation.ProgramID=Registration.ProgramID
AND Registration.ParticipantID=Participant.ParticipantId
我编写了以下 LINQ to SQL 来匹配上面的查询：
var trainingsiteinfo = (from c in db.ProgramLocations
from n in db.Registrations
from l in db.Participants
from h in db.Locations
where c.LocationID == h.LocationID
&& c.ProgramID == n.ProgramID
&& n.ParticipantID == l.ParticipantId
select new {
h.TrainingSite,
l.BackgroundTrainingID }).Distinct();
SQL 查询工作正常，但 LINQ 不断返回 null。
I have the following SQL query:
SELECT DISTINCT
Participant.BackgroundTrainingID,
Location.TrainingSite
FROM Registration, ProgramLocation, Participant, Program, Location
WHERE ProgramLocation.LocationID = Location.LocationID
AND ProgramLocation.ProgramID=Registration.ProgramID
AND Registration.ParticipantID=Participant.ParticipantId
I wrote the following LINQ to SQL to match the query above:
var trainingsiteinfo = (from c in db.ProgramLocations
from n in db.Registrations
from l in db.Participants
from h in db.Locations
where c.LocationID == h.LocationID
&& c.ProgramID == n.ProgramID
&& n.ParticipantID == l.ParticipantId
select new {
h.TrainingSite,
l.BackgroundTrainingID }).Distinct();
The SQL query works fine but LINQ constantly returns null.
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。
绑定邮箱获取回复消息
由于您还没有绑定你的真实邮箱，如果其他用户或者作者回复了您的评论，将不能在第一时间通知您！
发布评论
评论（3）
当我失去想法时，我使用 Linqer http://www.sqltolinq.com/ :-)加快转换作业。
I use Linqer http://www.sqltolinq.com/ when i get out of ideas :-) Aswell it speeds up conversion jobs.
在绑定结果之前，请确保您的数据库上下文没有超出范围。您可以通过在
.Distinct()之后添加.ToList()来强制提前加载结果来测试这一点。Make sure your db context isn't going out of scope before you have bound your results. You can test this by adding
.ToList()after your.Distinct()to force eager loading of the results.您的 linq 代码在 select 语句中有一个未闭合的 } 括号
Your linq code has an unclosed } bracket in the select statement