I'm looking for information on the cascade types that exist and how they work in relational modeling with JPA. The types I found explanations were:
NONE = Do not do anything with the object (default)
MERGE = Update children when updat...
When I make a Class Diagram or MER, the cardinality must be defined.
As an example: A doctor consults from 0 to n patients; a patient is consulted by 0 or 1 physician. Why 0?
I'm about to start developing an e-commerce, but I'm caught up in the issue of modeling, especially in product categories and subcategories. For example. A category can have several sub-categories. Each sub-category may also have sub-sub-categor...
Talk to people,
I need to create a structure template in which all my tables have a primary key consisting of id and version, so I can have multiple versions for each id.
Problem:
CREATE TABLE table1 {
id BIGSERIAL,...
Assuming I have a ternary relationship: two entities are NxN and the third entity is weak in relation to the relationship between these two.
I would like to know the difference between creating an aggregation between the two NxN entities and...
What is the best way to design Classes from the Database schema below:
Usuario(id INTEGER PK, desc TEXT);
Amigo(idA INTEGER, idB INTEGER, PK(idA,idB), FK(idA) REFERENCES Usuario(id));
This means that a user has 0 or more friends, when desig...
While studying 3FN, I came across 2 interesting examples and wondered if by making a small change, the examples would continue to serve 3FN.
Explanation about the 3FN concept
Explaining the Context
Below is an illustration presented b...
I have created a system that has sales control ( id , id_vendedor , produto ), vendor ( id , nome , id_equipe ) and team id , nome ) in a company.
Example: "João has id: 1 and belongs to the tea...
In my database, I need to store employees, customers, and suppliers. Since all of these share data in common, but are not all data, I have decided to create a pessoas table with the columns in common:
id // chave primária
tipo // tipo F...
For example, I have an invoice, which I can check in another database (but not mine), an example would be PagSeguro. I only store the invoice ID number so I can check it.
There is no doubt that storing this data that can be queried would con...