Since I designed my db, I came out with a self related model in my entity relational diagram. I have the entity country and the relation that go from country to the same country that is called passyingby and it has its own attributes transfer description.
So I would have tables:
country(nameCountry), passyingby(nameCountry1,nameCountry2,transfer_description).
How can I manage this in Laravel considering also the unique values of passyingby rows? I have created a migration to create the table country and its related model.
Related
I’m trying to map a relational database to an ontology.
I read many approaches like 1 2 and they all agreed to model bridge tables (join table between two tables connected with each other with many-to-many relationship) as follows:
If the bridge table contains exactly two foreign keys without presence of independent attributes, it can be mapped into two object properties, the latter is an inverse of the former.
If the bridge table contains exactly two foreign keys with presence of independent attributes, it should be mapped into separate OWL classes.
With that in mind, if we have two tables: students and courses and the join table contains only three columns:
id, student_id, course_id
we model the ontology with two classes: student and course, and two relationships "object properties" :
student ---study---> course
course ---studied_by---> student
but if the join table contains one independent attribute or more, let's say it contains:
id, student_id, course_id, grade
then a new class should be created in the ontology. we model the ontology with three classes: student, course, student_course and two object properties :
student ---student_has---> student_course
course ---course_has---> student_course
is this the best solution?
This feels like the wrong way of going about knowledge graph creation. This approach constrains you to the schema you have in your DB. Rather than relying on the shared attributes you have in your relational tables, you could start with a blank slate and design the ontology to your downstream use-case.
This paper from Stanford provides 7 clear steps how to create an ontology.. There are also a huge number of ontologies you can adapt to your use-case.
In terms of mapping data into the ontology, you could consider using something like RML.
I am trying to model with Laravel a database for purchases, in my mysql the relations are [ (for each table in the mysql i have one model)
so I was modeling in Laravel, for the associative table "fornecedor_item_detalhe" I used relation "belongstoMany", it worked out using tinker.
Now comes the problem:
together with the detalhes("fornecedor_detalhe") and the "items" I would like to be able to access the other tables related to "fornecedor_detalhe" which are "fornecedor" and "formpagto"."Has Many Through" will work For this?
And also I would like to link this associative table "fornecedor_detalhes-Item" in relation n: m with another table to create another associative table "fornecedor_detalhe_item_rci".
I've created a model for the pivot table "fornecedor_detalhe_item", but I'm not exactly sure how to do that, as long pivot tables don't have a primary key, how can i reference to them in the other pivot table
I did not codify anything, I'm just trying to model the same thing in laravel.
If you have any suggestions about MER I also accept it.
Thank you
just use Eloquent: Relationships
look in this link realtion types
and you should have model for fornecedor and formpagto
by build relation in model hasMany or belongsTo as your database structure you can call the anywhere just by type relation name
for example
in User Model
public function post()
{
return $this->hasMany(Post::class);
}
when you call in blade $user->post you get all posts related to this user and so on
I have a relation represented in MySQL that is
Classified belongsTo Category
Category hasMany Classifieds
Previously, I have had Classified.category_id set, but some Classifieds do not have Categories, and many Categories do not have any ads. This relationship is optional.
I have normalized the database to represent the database in a third table, categories_classifieds.
categories_classifieds
----
classified_id (primary, not null)
category_id (not null)
The reason this was normalized this way is to avoid null values, and also to
I am trying to create Models for the database in CakePHP 2, and there does not seem to be support for this simple relationship. Is this possible? Does the categories_classifieds join table need to be made into its own Model?
Thanks in advance for any insight.
Here are crow's-feet notation ER diagrams of the current, and proposed schemas:
http://i.stack.imgur.com/1BBVV.jpg
This is a hasAndBelongsToMany relation.
Make sure to follow cake's conventions though and make a seperate id field as primary key for the connecting model. You may not even need to have a model created for it and let it all to automagic after building the necessary relations in the models.
I had a pure junction table (to represent a many-to-many relationship) in my database. That is, a table with only two columns, each of them being a foreign-key, and them together composing the primary-key.
EF hid that complexity from me by not mapping this table to an entity, as expected; it was mapped as an Association.
Then I added a new column to this junction table in my database, and went on to Update Model From Database in the EDMX. But the table remained as an Association, not turning into an Entity with 3 properties.
What am I missing?
The thing is you need to delete the association first. Go to Model Browser > Your Model > Associations, find and delete the association. Then you can update the model and the table will show up as an entity.
Database tables:
Tutor( {PK}tutorId, name )
Module( {PK}moduleId, name, {FK}tutorId )
Relationship Tutor -> Module (OneToMany)
Questions:
If you create the domain model
classes with JPA annotations, the
corresponding database tables are
auto-created with the same columns as the annotated fields of the class?
Do you create the database first
and then the JPA classes with the
same fields as the database table
columns?
How do you model foreign key constraints with JPA
(1) and (2) are depended on your situation. you can create domain model class first and it will generate table and columns which are the similar to the fields. In addition, you can establish a database first (it is easy to design and have better view of the whole database.), then map the tables to your domain class.
about (3) you can try this link