many-to-many

问题 Hi I try use Many to Many relationship with EF Fluent API. I have 2 POCO classes. public class Project { public int ProjectId { get; set; } public virtual ICollection<Author> Authors { get; set; } public Project() { Authors = new List<Author>(); } } public class Author { public int AuthorId { get; set; } public virtual ICollection<Project> Projects { get; set; } public Author() { Projects = new List<Project>(); } } And I map many to many relationship with this part of code: ////MANY TO MANY

问题 I know that in elasticsearch, we can have child/parent relationships between documents. And then, when indexing, I can pass the parent id so that the child and parent documents are linked: $ curl -XPUT localhost:9200/blogs/blog_tag/1122?parent=1111 -d '{ "tag" : "something"}' Is there anyway to model a many to many relationship in elasticsearch? Data is resides in a MySQL database with the following schema: account ======== id name some_property group ======== id name description account

问题 I have 3 tables, 1) Customer (Id, Name, bla bla) 2) CustomerGroups (GroupId, GroupName) 3) CustomerInGroups (CustomerId, GroupId) using (var context = DataObjectFactory.CreateContext()) { context.Customers.Add(entity); context.SaveChanges(); return entity.Id; } How do I add a record into CustomerInGroups? EntityFramework doesn't generate entities for such many-to-many mapping tables Edit: Both the Id columns in Customer and CustomerGroups are set to auto increment. So in my CustomersGroup

问题 Here is a snippet of how my models are setup: class Profile(models.Model): name = models.CharField(max_length=32) accout = models.ManyToManyField( 'project.Account', through='project.ProfileAccount' ) def __unicode__(self) return self.name class Accounts(models.Model): name = models.CharField(max_length=32) type = models.CharField(max_length=32) class Meta: ordering = ('name',) def __unicode__(self) return self.name class ProfileAccounts(models.Model): profile = models.ForeignKey('project

问题 So, this is my first time learning computer language. And I chose python and django. Now, I got many of the basic concepts of python and also django. I can create new page with the views and all other stuff. But I am still confused with the relations, i.e. one to one, many to one, and many to many. Will someone please please please explain it to me. How can I use it? I really need to know. Thanks. 回答1: Especially with django, which makes complicated db design a piece of cake, I think it's

问题 I have a problem with many to many relationship in EF core. I have the following model classes: public class Meal { public int Id { get; set; } [Required] public int Insulin { get; set; } public MealType Type { get; set; } public ICollection<MealFood> MealFoods { get; set; } public Meal() { MealFoods = new Collection<MealFood>(); } } public class Food { public int Id { get; set; } [StringLength(255)] public string Name { get; set; } [Required] public int Carbohydrates { get; set; } public

问题 Referring to https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/bp-adjacency-graphs.html. I was wondering if anyone could help me. The first image is of the table, and the second is the GSI. Here is the table: On the table, I don't understand how one is to create the sort-key? Is this one attribute that stores both Bill-ID and Invoice-ID? or two separate attributes? I have a feeling it's the one flexible attribute, and if so how do you differentiate one from the other? And how

问题 Referring to https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/bp-adjacency-graphs.html. I was wondering if anyone could help me. The first image is of the table, and the second is the GSI. Here is the table: On the table, I don't understand how one is to create the sort-key? Is this one attribute that stores both Bill-ID and Invoice-ID? or two separate attributes? I have a feeling it's the one flexible attribute, and if so how do you differentiate one from the other? And how

问题 Setup Access 2007 This is a simplified scenario. It is nearly identical to my actual use case just easier to explain. I have a many to many relationship between movies and genres the table structure is below. Table: movies id autonumber name text Table: genres id autonumber name text Table: movie_genres movie_id number genre_id number I would like a form that allows me to list all genre's for a given movie. But also allows me to create new genre's without opening a separate form. Similar to

问题 I have a database with Rounds and Users. Rounds belongsToMany Users and Users belongsToMany Rounds, so a many-to-many relation. A join table rounds_users was added to do this. EDIT: Used the incorrect phrase here. I meant 'belongsToMany' instead of 'hasMany' Now I want to retrieve a list of Rounds, together with the number of linked Users per round. In case of a one-to-many relation something like the following would work: $rounds = $this->Rounds->find() ->contain(['Users' => function ($q) {