many-to-many

问题 I am building a SQLite database and am not sure how to proceed with this scenario. I'll use a real-world example to explain what I need: I have a list products that are sold by many stores in various states. Not every Store sells a particular Product at all, and those that do, may only sell it in one State or another. Most stores sell a product in most states, but not all. For example, let's say I am trying to buy a vacuum cleaner in Hawaii. Joe's Hardware sells vacuums in 18 states, but not

问题 I have this entity in my symfony project: /** * Batiments * * @ORM\Table(name="batiments") * @ORM\Entity * @ORM\Entity(repositoryClass="MySpace\DatabaseBundle\Repository\BatimentsRepository") */ class Batiments { /** * @var integer * * @ORM\Column(name="id", type="integer", nullable=false) * @ORM\Id * @ORM\GeneratedValue(strategy="IDENTITY") */ private $id; /** * @var string * * @ORM\Column(name="nom", type="string", length=150, nullable=true) */ private $nom; /** * @ORM\ManyToOne

问题 I have been working on a many to many mapping on an entity i have called Task. A task can have many children and many parents. There is a join table in between which just has the two FK columns "ParentTaskId" and "ChildTaskId". Here is what I have come up with so far. // Many-to-Many Parents HasManyToMany<Task>(x => x.Parents) .Table("TaskDependency") .ParentKeyColumn("ParentTaskId") .ChildKeyColumn("ChildTaskId") .Inverse() .Not.LazyLoad() .Cascade.SaveUpdate(); // Many-to-Many Children

问题 As an example, let's say I have a fact table with two dimensions and one measure FactMoney table ProjectKey int PersonKey int CashAmount money The two dimensions are defined like this: DimProject (a type 0 dimension - i.e. static) ProjectKey int ProjectName varchar(50) DimPerson (a type 2 slowly changing dimension) PersonKey int PersonNaturalKey int PersonName varchar(50) EffectiveStartDate datetime EffectiveEndDate datetime IsCurrent bit Pretty straightforward so far. Now I'll introduce a

问题 OK this problem has it all. Conceptually I have a Resource entity which can have many Child Resources and many Parent Resources. The Resource table has two fields, ID and Name with ID being the primary key. To complete the many to many relationship I created a ResourceHierarchy table which has two fields, (Parent_ID, Child_ID) and two foreign keys with each one referencing the primary key of the Resource table (ID) and the ResourceHierarchy table has a composite primary key of (Parent_ID,

问题 In my database I have the following tables: Customers (ID) Orders (ID) CustomersOrders (CustomerID, OrderID) How do I map Customers table to Customers class and Orders table to Orders class without creating a class CustomersOrders? 回答1: That depends on which LINQ version you're talking about. If you're using Entity Framework 4.0 and you have no additional information in the table other than the IDs then what you are asking for should already be generated. I believe the same is true for Entity

问题 I'm sorry for my bad English, I'm not a native speaker. Feel free to correct my text if needed. The question is really simple (it's in the end of this text), but I've written a rationale with some research and tests. Rationale If you want, you can skip this rationale and jump directly to the question itself. I've been trying for several hours on trying to get a ManyToMany relationship to persist from the inverse side using doctrine:generate:entities and doctrine:generate:crud on Symfony2

问题 I have two models. User and Account as follows class Account < ActiveRecord::Base has_many :manages has_many :users, :through => :manages end class User < ActiveRecord::Base has_many :manages has_many :accounts, :through => :manages end If I were to use the rails console and create an instance of account by acc = usr.accounts.build acc.save The following command would return the account instance created usr.accounts But the following command would not return the user instance acc.users Also

问题 I am writing small app, using Play Framework 2.0 which uses Ebean as ORM. So I need many-to-many relationship between User class and UserGroup class. Here is some code: @Entity public class User extends Domain { @Id public Long id; public String name; @ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL) public Set<UserGroup> groups = new HashSet(); } @Entity public class UserGroup extends Domain { @Id public Long id; public String name; @ManyToMany(mappedBy="groups") public Set

问题 I have three tables: friends , locations , friend_location friend_location is a join table to allow the many-to-many relationship between friends and locations , so the tables will look something like this: Friends ID | Name 1 | Jerry 2 | Nelson 3 | Paul location ID | Date | Lat | Lon 1 | 2012-03-01 | 34.3 | 67.3 2 | 2011-04-03 | 45.3 | 49.3 3 | 2012-05-03 | 32.2 | 107.2 friend_location Friend_ID | Location_id 1 | 2 2 | 1 3 | 3 2 | 2 What I would like to do is get the latest location for each