many-to-many

I have two tables ( persons and projects ) which are in a many-to-many table, thus linked together by a third table persons_projects In ms access I now created a form showing data from the projects table. What I want is to have a subform showing all persons - datasets which participate in this project. In this subform it should also be possible to add (or delete) persons from this project—a drop-down seems the best choice here. How can I do this? I’m able to show all participants, but I’m not able to add them. seems like I have the “insert into view” problem again, since I need persons and

@Entity class A { @ManyToMany private List<B> list; ... } @Entity class B { ... } I'd like to get list from A class using criteria (not sql query). Is it posible to do this? Projection in this case does not work. Unfortunately, The Criteria only allows selecting the root entity, and not any joined entity. It would thus be easier if your ManyToMany was bidirectional. You could the use the criteria equivalent of select b from B b inner join b.as a where a = :theA If that's not an option, I think the only way is to use a subquery, and thus code the criteria equivalent to select b from B b where b

I've created a simple DB in EF code first but appear to have hit a problem. What I would like to do is, query the DBContext to retrieve a custom object CheckedTag that would have all of the available tags and a boolean field of checked. Code First abstracts the Many-To-Many table and I can't seem to find the correct query. I've tried var qry = from t in Db.Tags from a in Db.Articles where(a.Id == articleId) select new CheckedTag { Id = t.Id, Name = t.Name, PermanentUrl = t.PermanentUrl, Checked = t.Id == null ? false : true }; and scoured the net for a few hours now. If the articleId were to

I have 2 Tables in Postgres: CREATE TABLE "images" ( "id" serial NOT NULL PRIMARY KEY, "title" varchar(300) NOT NULL, "relative_url" varchar(500) NOT NULL) and CREATE TABLE "tags" ( "id" serial NOT NULL PRIMARY KEY, "name" varchar(50) NOT NULL) To establish many to many relationship between images and tags I have another table as: CREATE TABLE "tags_image_relations" ( "id" serial NOT NULL PRIMARY KEY, "tag_id" integer NOT NULL REFERENCES "tags" ("id") DEFERRABLE INITIALLY DEFERRED, "image_id" integer NOT NULL REFERENCES "images" ("id") DEFERRABLE INITIALLY DEFERRED) Now I have to write a query

I am struggling with mappings for the following sql tables |Post | |PostRelation | |------------------| |-----------------| |PostId |1--------*|ParentPostId | |---other stuff--- |1--------*|ChildPostId | | | |RelationType | Ideally Id like a property on post called relatedPosts as Dictionary <RelationType,IList<Post>> But at the minute Id just settle for a property on post with an IList<PostRelation>. I successfully used a many to many to get related posts, but this method loses the addtional data. Any suggestions?? I Finally found a solution after much research. So though I would post it in

Dunno how to name this properly. I have two entities in m:n relationship: Member and Role. public class Role { public int Id { get; set; } public string Title { get; set; } public ICollection<Member> MembersInRole { get; set; } } public class Member { public int Id { get; set; } public string Name { get; set; } public string Password { get; set; } public string Email { get; set; } public ICollection<Role> Roles { get; set; } } I have made some seed data: http://i56.tinypic.com/2vjvj1w.png And wrote test: The problem is, that my Member entity has no roles assigned, even when I created them in