many-to-many

问题 My Entity Model is as follows: Person , Store and PersonStores Many-to-many child table to store PeronId,StoreId When I get a person as in the code below, and try to delete all the StoreLocations, it deletes them from PersonStores as mentioned but also deletes it from the Store Table which is undesirable. Also if I have another person who has the same store Id, then it fails saying "The DELETE statement conflicted with the REFERENCE constraint \"FK_PersonStores_StoreLocations\". The conflict

问题 I have a few ORM mapped tables, which (pared down) look like this: class Tag(Base): __tablename__ = 'tags' tag_name = Column(String, primary_key=True) task2tag_assoc = Table('tasktags', Base.metadata, Column('task_id', UUID, ForeignKey('tasks.task_id', ondelete='cascade'), primary_key=True), Column('tag_name', String, ForeignKey('tags.tag_name', ondelete='cascade'), primary_key=True) ) class Task(Base): __tablename__ = 'tasks' task_id = Column(UUID, primary_key=True) _tags = relationship('Tag

问题 After merging an entity that has related entities with relations set to cascade both persist and merge operations the relations are lost! Here are the entities: class Event implements NormalizableInterface { /** * @ORM\ManyToMany(targetEntity="Participant", inversedBy="events", cascade={"persist", "merge"}) * @ORM\JoinTable(name="event_participant", * joinColumns={@ORM\JoinColumn(name="event_id", referencedColumnName="id", onDelete="CASCADE")}, * inverseJoinColumns={@ORM\JoinColumn(name=

问题 My team has two classes, User and Store , related by JPA @ManyToMany annotations. The relevant code is below. When creating a new User object and setting its stores, life is good. But we're seeing some unexpected behavior when trying to update User objects through our Struts 2 / Spring web UI. (These problems do not occur when running simple automated integration tests through JUnit). Simply put, when saving a User , its stores collection is not updated -- the database shows no changes, and

问题 I have a many-to-many between foo and bar modeled as a table foo_bar with foo_id and bar_id . I'd now like to model this as a one-to-many (which my data allows). I've added a foo_id column to bar but now I want to migrate my data. So, I want to UPDATE bar SET foo_id = f where id = b; where each f and b pair are coming from SELECT foo_id AS f, bar_id AS b FROM foo_bar; Is it possible to do this in SQL (and specifically PostgreSQL 9.0)? I know how to do sub-SELECTs in UPDATEs when there's only

问题 Here is the situation: I have an entity Property class Property { /** * @ORM\Id * @ORM\Column(type="string") * @ORM\GeneratedValue(strategy="UUID") */ protected $id; /** * @ORM\ManyToMany(targetEntity="PropertyEquipment", inversedBy="properties") */ protected $propertyEquipments; public function __construct() { $this->propertyEquipments = new ArrayCollection(); } public function getId() { return $this->id; } public function addPropertyEquipment(\AppBundle\Entity\PropertyEquipment

问题 (link to previous question just in case: Struggling with one-to-many relation in an admin form) I have this many-to-many relation in my Symfony-1.3 / Propel-1.4 project between User and Partner . When the User is being saved, if it has certain boolean flag being true, I want to clear all the links to the partners. Here is what I do at the moment and it doesn't work: // inside the User model class public function save(PropelPDO $con = null) { if ($this->getIsBlaBla()) { $this-

问题 I have a post/tag database, with the usual post, tag, and tag_post tables. The tag_post table contains tagid and postid fields. I need to query posts. When I want to fetch posts that have a certain tag, I have to use a join: ... INNER JOIN tag_post ON post.id = tag_post.postid WHERE tag_post.tagid = {required_tagid}` When I want to fetch posts that have tagIdA and tagIdB, I have to use two joins (which I kind of came to terms with eventually). Now, I need to query posts that do not have a

问题 When setting up a many-to-many relationship with Code First approach, by default the join table only includes 2 columns (FK to PK of the 2 tables). 1) Is it possible/How can I setup a join table that will include some additional fields, and 2) how do I fill these values via code? For example: class Student { public int Id { get; set; } public string Name { get; set; } public List<Course> Courses { get; set; } } class Course { public int Id { get; set; } public string Name { get; set; } public

问题 I have an Invoice master model and its admin. In the Invoice detail(Inline), I wish to select distinct products from Product table i.e In each Invoice detail, I should not allow to select product that has been previously selected. Can I get sample code for it? Relations defined: models.py: class InvoiceHeader(models.Model): #model number .... class InvoiceDetail(models.Model): header = models.ForeignKey(InvoiceHeader) products = models.ManyToManyField(Product,related_field="products") admin