foreign-key-relationship

Using Schema First , I have a database structure, as so ExternalDataItems --- edataitem_id PK -- surrogate auto-increment - NOT for FK relation here datahash UX -- Candidate Key / Unique Index (binary(20)) ExternalMaps --- emap_id PK ext_datahash FK on ExternalDataItems.datahash - NOT referencing the surrogate PK and after generating the SSDL/CSDL 1 has this <Association Name="FK_ExtMaps_ExtDataItems"> <End Multiplicity="1" Role="ExternalDataItems" Type="Store.ExternalDataItems" /> <End Multiplicity="*" Role="ExternalMaps" Type="Store.ExternalMaps" /> <ReferentialConstraint> <!-- error on this

I have a many-to-many relationship between User & Role, with a role_user table. My migrations are setup as so (simplified): users table: public function up() { Schema::create('users', function(Blueprint $table) { $table->increments('id'); $table->string('email')->unique(); }); } roles table: public function up() { Schema::create('roles', function(Blueprint $table) { $table->increments('id'); $table->string('name'); }); } role_user table: public function up() { Schema::create('role_user', function(Blueprint $table) { $table->increments('id'); $table->integer('user_id')->unsigned(); $table-

I have Flight, Person, and Glider models in a Rails 3 app. I've defined custom relationships because I need more than one foreign key referencing a Person from the flights table. Associations work but ONE-WAY only. class Flight < ActiveRecord::Base belongs_to :pilot, :class_name => "Person" belongs_to :instructor, :class_name => "Person" belongs_to :towplane_pilot, :class_name => "Person" belongs_to :airplane_instructor, :class_name => "Person" belongs_to :glider belongs_to :rep_glider, :class_name => "Glider" belongs_to :departure_airfield, :class_name => "Airfield" belongs_to :arrival

I have been successfully using NHibernate for quite some time now and have been able to solve a lot of pitfalls with an application that I developed with it and that is running in production. The recent hurdle really has me scratching my head, though. Recently I had to expand the class library with some new classes that are nested as children to some already existing classes. I just copied the same model for aggregate mapping that I already was successfully using, but this time it does not work. Now when I use the following in the parent mapping file: <bag name="SeaInfoItems" table="EDIImport

i'm starting now on Rails, i looked in the forum, but i didn't find anything that could solve my problem. Here it goes, I have a Category table, and it has only name for a column (there is no repetition in categories) so i would like name to be the primary key, then i have a Product table that has name, main_photo, description and i would like to say that a product only has a category, do i need to add a column named category as a foreign key in products? A Category is suposed to have many products. Then in category models how do i say that name is the primary Key, and how can i do the

I have a set of tables that look like: workflows = Table('workflows', Base.metadata, Column('id', Integer, primary_key=True), ) actions = Table('actions', Base.metadata, Column('name', String, primary_key=True), Column('workflow_id', Integer, ForeignKey(workflows.c.id), primary_key=True), ) action_dependencies = Table('action_dependencies', Base.metadata, Column('workflow_id', Integer, ForeignKey(workflows.c.id), primary_key=True), Column('parent_action', String, ForeignKey(actions.c.name), primary_key=True), Column('child_action', String, ForeignKey(actions.c.name), primary_key=True), ) My

Starting from an existing (SQLite) database with foreign keys, can SQLAlchemy automatically build relationships ? SQLAlchemy classes are automatically created via __table_args__ = {'autoload': True} . The goal would be to easily access data from related tables without having to add all the relationships one by one by hand (i.e. without using sqlalchemy.orm.relationship() and sqlalchemy.orm.backref ). vvladymyrov [Update] As of SQLAlchemy 0.9.1 there is Automap extension for doing that. For SQLAlchemy < 0.9.0 it is possible to use sqlalchemy reflection. SQLAlchemy reflection loads foreign