relations

When are records from related tables loaded with LINQ2SQL

Let's say I have two tables: Report Comment And assuming I have a database context: var reports = db.Reports(); How can I make sure all Comments for each report are loaded as well? At this point I want to disconnect from the database but still have access to the comments. (For example:) reports[0].Comments[0].Subject ...

SQL database problems with addressbook table design

Hello! I am writing a addressbook module for my software right now. I have the database set up so far that it supports a very flexible address-book configuration. I can create n-entries for every type I want. Type means here data like 'email', 'address', 'telephone' etc. I have a table named 'contact_profiles'. This only has two colu...

Sequential numbering in database (MSACCESS)

Summary: I have a table that has a uique primary key identifying each record. I also have three more fields that can identify a record: Category CategoryNumber DuplicateNumber When I add a new record and choose the Category, how can I get CategoryNumber to increment correctly based on whether it is a duplicate or not. Note that thi...

Implementing foreign key type relationships in XSD schema

I'm trying to wrap my head around xml schemas and one thing I'm trying to figure out is how to do relational type schemas where on element refers to another, possibly in another schema altogether. I've looked at the xsd:key and xsd:keyref and it seems like the sort of thing I'm interested in, but I'm not sure. Initially I just set attrib...

Why are positional queries bad?

I'm reading CJ Date's SQL and Relational Theory: How to Write Accurate SQL Code, and he makes the case that positional queries are bad for example, this INSERT: INSERT INTO t VALUES (1, 2, 3) Instead, you should use attribute-based queries like this: INSERT INTO t (one, two, three) VALUES (1, 2, 3) Now, I understand that the first...

MySQL joins, how to output relation "the proper way"

Hello, First of all, excuse my poor topic title. I simply have no idea how to formulate this question or what to Google after, so don't shoot me if this is something easy answerable. Assume I have the following tables: [AUTHORS] id, name [NEWS] id, item, author_id If I wanted to display a news item and output the corresponding autho...

relations on sets need help asap on relations on sets

this my question i dont know what to do Let A = {1, 2, 3, 4, 6} and let R be the binary relation on A defined by“x divides y”. (x divides y if and only if there exists an integer z such that xz = y). i. Write R as a set of ordered pairs. ...

Referencing table with two different foreign keys to the same table in Kohana ORM

table user: |id|name|employee_priority_id|user_priority_id| table priority: |id|name| As you can see, there are two foreign fields to the same table. But Kohana ORM default looks for a field called priority_id, which doesn't exist. Is there a way to let Kohana ORM know that those two fields are an foreign key to that table. ...

PHP / Doctrine ORM multiple 'one-to-one' relations to the same class

Just working on a project where I have a class called 'Product' and a class called 'Image'. Each product has two types of images, one 'front' image and one 'back' image, so I defined two fields, one called image_front_id and one called image_back_id. In the method BaseProduct::setUp(), I defined the relation for the front images as foll...

Doctrine ORM - Implement self-relations

Hi everyone! Can anyone give me an example of how to implement a class self-relation? Thanks in advance, Best regards! ...

Castle ActiveRecord OneToOne and JoinedBase/Key all together, No SQL Relations Created

I'd like to model the following relationship. [JoinedBase] MasterForm{ Guid MasterFormId {get;set;} /* some base properties like modifiedBy etc... */ } [ActiveRecord] TerminationForm{ [PrmaryKey(Foreign)] Guid MasterFormId {get; set;} /* Some more properties specific to terminations */ } [ActiveRecord("TermStaffing")] ...

Cascade delete in Ruby ActiveRecord models?

I was following the screencast on rubyonrails.org (creating the blog). I have following models: comment.rb class Comment < ActiveRecord::Base belongs_to :post validates_presence_of :body # I added this end post.rb class Post < ActiveRecord::Base validates_presence_of :body, :title has_many :comments end Relations ...

Relations between tables

Hello, I have 3 tables: A, B and C. Table A is in relation (n:1) with B and with C. Typically I store in A the B.Id (or the C.Id) and the table name. e.g. A.ParentId = 1 A.TableName = "B" A.ParentId = 1 A.TableName = "C" A.ParentId = 2 A.TableName = "B" Is it a good solution? Are there any other solutions? Thanks in advance ...

How to get the tag relations results just by using SQL(s)?

Table tags: article_id tag 1 Language 1 Java 1 c++ 2 Language 2 c++ 3 c++ and how can I write SQL(s) query(s) to make the data like below: Table tags_relations: tag1 tag2 relations_degree Language C++ 2 Language Java 1 note: if...

Using Include() with inherited entities problem

In EF eager loading related entities is easy. But I'm having difficulties including inherited entities when loading data using table-per-type model. This is my model: Entities: ArticleBase (base article entity) ArticleSpecial (inherited from ArticleBase) UserBase (base user entity) UserSpecial (inherited from UserBase) Image R...

CakePHP belongsTo relationship with a variable 'model' field.

I've got a problem with a belongsTo relationship in CakePHP. I've got an "Action" model that uses the "actions" table and belongs to one of two other models, either "Transaction" or "Tag". The idea being that whenever a user completes a transaction or adds a tag, the action model is created to keep a log of it. I've got that part workin...

Database structure - To join or not to join

Hi! We're drawing up the database structure with the help of mySQL Workbench for a new app and the number of joins required to make a listing of the data is increasing drastically as the many-to-many relationships increases. The application will be quite read-heavy and have a couple of hundred thousand rows per table. The questions:...

Doctrine toarray does not convert relations.

Hi, so..I followed doctrine documnetation to get started. Here is the documentation http://www.doctrine-project.org/documentation/manual/1_2/en/working-with-models#dealing-with-relations:retrieving-related-records My code is $User = Doctrine_Core::getTable("User")->find(1); when I access relations by $User->Phonenumbers, it works. ...

Creating multiple relationships in rails with same datatypes

What I am trying to do is kind of like this: I have datatypes "user" and "article" for instance. I want to have relationships between these two, but in more than one way. So for instance, I'd like to let a user "like" or "bookmark" an article. So I need to have two relations in the database, one for users liking the article, and one fo...

How can I store in a db several phone numbers to be related to their own restaurants?

I have a table called "restaurants" which contains each restaurant information, I want to add its phone numbers. Should I make another table called say "phones" with fields "phone1", "phone2", "phone3", etc, then make a relation between them? or their is an easier way to do this? Thanks a lot :) ...