relationships

How would I go about creating a polymorphic has_and_belongs_to_many relationship with Rails/ActiveRecord? Most of the examples I see involve creating a belongs_to relationship which limits my polymorphic-side to being related to only one parent: Table: Task Table: Tasks_Targets Table: CustomerStore Table: SoftwareSystem Both CustomerStore and SoftwareSystem would be of type "Targetable" in this circumstance. From what I understand, if I implement the polymorphic relationship as most examples show, I'd only be able to relate a Targetable to a Task once . Some clarification might help as most

I'm building an app that requires a core data relationship as such: entityA <<---> entityB (e.g. any given entityA can hold many entityB objects) I have two tableviews with entityA list items in which I want to be able to store entityB objects in any given entityA object. I'm new to using relationships with core data (and fairly new to swift) and would like to learn how to make this work. Does anyone have any swift tutorials in mind that would be good for me to take a look at or any other resources that may help me learn? Sorry if my question doesn't make much sense, ask me to clarify if you

Related question: Multivalued Fields a Good Idea? I know that multi-valued fields are similar to many-to-many relationship. What is the best way to replace multi-valued fields in an MS Access application? I have an application that has multi-valued fields. I am not sure how exactly to do away with those and implement exactly same logic in the form of fields that are single-valued? What would be the implementation in terms of table-relationships when I want to move a multi-valued relationship to single-valued one. Thank you. Fionnuala The following is probably far more detailed than you need,

可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试): 问题: I'm having difficulties retrieving relationships when the relationship type is annotated with a @RelationshipType field. The relationships look correct in Neoclipse, but I'm retrieving no results in my application. The code that doesn't work is (simplified): @NodeEntity public abstract class Entity { @RelatedToVia private Collection<Relationship> relationships; public Relationship relatedTo(Entity entity, String type) { Relationship relationship = new Relationship(type, this, entity); relationships.add(relationship); return relationship; } .

I have two related problems I need help with. Problem 1: How do I model a conditional relationship? I want my data to indicate that when test CLT1's "Result" property = "High", CLT1 has relationship to Disease A. If I take a node-centric approach, I imagine that the code might look something like... (CLT 1 {Result: "High"}) -[:INDICATES] -> (Disease A) Further, when CLT1's "Result" property = "Low", CLT1 has a relationship to Disease B (CLT 1 {Result: "Low"}) -[:INDICATES] -> (Disease B) Alternatively, if I take a relationship-centric approach, the code might look like this... (CLT 1) -[

I'm attempting to use Neo4j to model the relationship between projects, staff, and project roles. Each project has a role called "project manager" and a role called "director". What I'm trying to accomplish in the data model is the ability to say "for project A, the director is staff X." For my purposes, it's important that "project", "staff", and "role" are all entities (as opposed to properties). Is this possible in Neo4j? In simpler terms, are associative entities possible in Neo4j? In MySQL, this would be represented with a junction table with a unique id column and three foreign key

For example a list and a sublist can have many items through a model called list_items. Here are the models class List < ActiveRecord::Base has_many :sublists has_many :list_items has_many :items, through: :list_items end class Sublist < ActiveRecord::Base belongs_to :list has_many :list_items has_many :items, through: :list_items end class Item < ActiveRecord::Base has_many :list_items has_many :lists,through: :list_items has_many :sublists, through: :list_items end class ListItem < ActiveRecord::Base belongs_to :list belongs_to :sublist belongs_to :item end This below is what i am trying to

I have a 1..* relationship between User and Post . (one user has many posts) Post has a FK called "UserId", which maps to the "UserId" field on User table. I tried to set this FK as Cascade UPDATE/DELETE, but i get this error: 'Users' table saved successfully 'Posts' table - Unable to create relationship 'FK_Posts_Users'. Introducing FOREIGN KEY constraint 'FK_Posts_Users' on table 'Posts' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints. Could not create constraint. See previous errors. I have a table