Linq.How to complete this query?

[shapper]

Hello,

I have 3 tables with a many to many relationship:

Professors ProfessorID, Age, ...
Tags TagID, Name, ...
ProfessorsTags ProfessorID, TagID

How can I get all the professors and all tags associated to each
professor using LINQ?

I have the following:

List<ProfessorP aperpapers = (from p in database.Profes sors
orderby p.Name
select new ProfessorPaper {
Professor = p,
Tags = new List<Tag{

}
}
}).ToList();

ProfessorPaper is a wrapper that contains two properties: Professor
and List<Tag>.
In my query what I am missing is filling the tags for each professor.

Could someone, please, tell me how to do this?

Thanks,
Miguel

[Jon Skeet [C# MVP]]

Re: Linq.How to complete this query?

On Jun 27, 1:15 am, shapper <mdmo...@gmail. comwrote:

Hello,
>
I have 3 tables with a many to many relationship:
>
Professors ProfessorID, Age, ...
Tags TagID, Name, ...
ProfessorsTags ProfessorID, TagID
>
How can I get all the professors and all tags associated to each
professor using LINQ?
>
I have the following:
>
      List<ProfessorP aperpapers = (from p in database.Profes sors
                                          orderby p.Name
                                          select new ProfessorPaper {
                                            Professor = p,
                                            Tags = new List<Tag{
>
                                            }
                                          }
                                          }).ToList();
>
ProfessorPaper is a wrapper that contains two properties: Professor
and List<Tag>.
In my query what I am missing is filling the tags for each professor.
>
Could someone, please, tell me how to do this?

Well, you could try:

Tags = from pt in database.Profes sorsTags where pt.Professor == p
select pt.Tag

I don't know how nicely that will translate into SQL though.

Alternatives will depend on how you've mapped the ProfessorsTags
collection. For instance, if you've got two many-to-one relationships
mapped, and you've made both of them bidirectional, you may be able to
do:

Tags = p.ProfessorsTag s.Tags

Again, I don't know offhand what the SQL for this would look like.

Jon

[shapper]

Re: Linq.How to complete this query?

On Jun 27, 6:47 am, "Jon Skeet [C# MVP]" <sk...@pobox.co mwrote:

On Jun 27, 1:15 am, shapper <mdmo...@gmail. comwrote:
>
>
>

Hello,

>

I have 3 tables with a many to many relationship:

>

Professors ProfessorID, Age, ...
Tags TagID, Name, ...
ProfessorsTags ProfessorID, TagID

>

How can I get all the professors and all tags associated to each
professor using LINQ?

>

I have the following:

>

      List<ProfessorP aperpapers = (from p in database.Profes sors
                                         orderby p.Name
                                         select new ProfessorPaper {
                                           Professor = p,
                                           Tags = new List<Tag{

>

                                           }
                                         }
                                         }).ToList();

>

ProfessorPaper is a wrapper that contains two properties: Professor
and List<Tag>.
In my query what I am missing is filling the tags for each professor.

>

Could someone, please, tell me how to do this?

>
Well, you could try:
>
Tags = from pt in database.Profes sorsTags where pt.Professor == p
select pt.Tag
>
I don't know how nicely that will translate into SQL though.
>
Alternatives will depend on how you've mapped the ProfessorsTags
collection. For instance, if you've got two many-to-one relationships
mapped, and you've made both of them bidirectional, you may be able to
do:
>
Tags = p.ProfessorsTag s.Tags
>
Again, I don't know offhand what the SQL for this would look like.
>
Jon

Thanks Jon. I will try it