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Questions tagged [relationship]

Questions in this tag typically involve the association that a set of data has with other set(s) of data.

5577 questions
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Laravel Eloquent ORM replicate

I have a problem with replicating one of my models with all the relationships. The database structure is as follows: Table1: products id name Table2: product_options id product_id option Table3: categories id name Pivot table:…
Zoli
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Java sockets: multiple client threads on same port on same machine?

I am new to Socket programming in Java and was trying to understand if the below code is not a wrong thing to do. My question is: Can I have multiple clients on each thread trying to connect to a server instance in the same program and expect the…
espcorrupt
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How do I rename relationships in Neo4j?

I realized only after importing a ton of nodes that I had created relationships called START, which is a reserved keyword. Querying the DB through the Cypher console hence always complains about the reserved keywords: SyntaxException: reserved…
ulkas
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What is the best way to implement many-to-many relationships using ORMLite?

I'm currently playing with ORMlite to make a model with tables and relationships. One relationship is a many-to-many relationship. What's the best way to implement that? To be more concrete: Let's say I've got these two tables Product id …
Romain Piel
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Rails, how to avoid the "N + 1" queries for the totals (count, size, counter_cache) in associations?

I have a these models: class Children < ActiveRecord::Base has_many :tickets has_many :movies, through: :tickets end class Movie < ActiveRecord::Base has_many :tickets has_many :childrens, through: :tickets belongs_to…
user4412054
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1 answer

CoreData optional to-many relationships can never be nil?

Quirk I just discovered, and wanted to confirm with anyone here whether or not this is avoidable. Basically, if I have a very simple two entity model: With a to-many relationship between Entity1 and Entity2. The relationship is optional, with…
Jonathan Crooke
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Calculate Family Relationship from Genealogical Data

I would like to be able to calculate the family relationship between two individuals in a family tree, given the following data schema (simplified from my actual data schema, only showing columns that directly apply to this…
defines
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Cosine similarity vs Hamming distance

To compute the similarity between two documents, I create a feature vector containing the term frequencies. But then, for the next step, I can't decide between "Cosine similarity" and "Hamming distance". My question: Do you have experience with…
caw
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Entity Framework Core: Update relation with Id only without extra call

I'm trying to figure out how to deal with 'Single navigation property case' described in this doc: Let's say we have 2 models. class School { public ICollection Childrens {get; set;} ... } and class Child { public int Id {get;…
silent_coder
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How to find its owner DataGrid and DataGridRow from DataGridCell in WPF?

In an event handler for a Command for a DataGrid, I get DataGridCell in ExecutedRoutedEventArgs. However, I couldn't figure out how to get its associated DataGrid and DataGridRow. Your help is much appreciated.
newman
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SQLSTATE[42000]: Syntax error or access violation: 1066 Not unique table/alias on relationship

So, I'm receiving the following error from Laravel framework; but I couldn't find why this framework is producing this error: SQLSTATE[42000]: Syntax error or access violation: 1066 Not unique table/alias: 'participants' (SQL: select…
ChrisBratherton
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neo4j: one-directional / two-directional relationships?

So I looked into neo4j, and I may be using it in an upcoming project since its data model might fit my project very well. I looked through the docs but I still need an answer to this question: Can I set relationships to be one-directional? It seems…
joschua011
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Room relations with conditions

How to add conditions to the relation? For example, we have object Pet @Entity public class Pet { @ PrimaryKey int id; int userId; String name; String type; // other fields } and…
waldemar
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SQLAlchemy: add a relationship using id instead of object?

Is it possible to add to a SQLAlchemy relationship using ids rather than objects? For example, consider two declarative SQLAlchemy classes, Review and Artist, with a relationship between them: class Review(Base): artist_id = Column(Integer,…
Ollie Glass
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How are `ghc-pkg` and `cabal` programs related? (Haskell)

As I know cabal is a program to manage installation of packages like FreeBSD's pkg_add. But there is another tool called ghc-pkg. I don't know why there are two different programs. What's the role of each of them and how are they related?
eonil
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