- How do you implement categories in a database?
- What is a category in a database?
- How do you store categories and subcategories in a database?
- What is a Category table?
- How do I categorize in MySQL?
- What kind of databases are there?
- What is aggregation in DBMS?
- What is sub sub category?
- How do I create a category and subcategory in HTML?
- How can we save trees in relational database?
How do you implement categories in a database?
You should use either nested sets or parent-child models. I used to implement both of them.
Make a categories table with the following fields:
- CategoryID - Integer.
- CategoryName - String/Varchar/Whatever.
- ParentID - Integer.
What is a category in a database?
Data categories are tables of data, which are organized by rows and columns. Columns are also known as data fields. A row of data has entries for one or more columns in the category. When you add a data field onto a report you are seeing the information in one column of data for every row in the category.
How do you store categories and subcategories in a database?
- only use one table, which references itself, so that you can have unlimited depth of categories.
- use technical ids (using IDENTITY , or similar), so that you can have more than 10 subcategories.
- if required add a human readable column for category-numbers as separate field.
What is a Category table?
The category table lists the categories that can be assigned to a film. The category table is joined to the film table by means of the film_category table.
How do I categorize in MySQL?
Let's tackle this, select all categories regardless of the parent. Add all the results as an array and pass them to a function called generateTree. $categories = $db->query('SELECT id, parent_id, category FROM categories ORDER BY category'); $rows = $categories->fetchAll(PDO::FETCH_ASSOC); echo generateTree($rows);
What kind of databases are there?
Types of databases
- Centralised database.
- Distributed database.
- Personal database.
- End-user database.
- Commercial database.
- NoSQL database.
- Operational database.
- Relational database.
What is aggregation in DBMS?
Aggregation in DBMS
Aggregation refers to the process by which entities are combined to form a single meaningful entity. The specific entities are combined because they do not make sense on their own. To establish a single entity, aggregation creates a relationship that combines these entities.
What is sub sub category?
For one, subcategory is a class of things, not a thing, itself. The prefix "sub-" indicates that all of the things in this class also belong to another, broader class of things. It does not infer how broad or narrow the parent class is. So, grammatically, a subcategory of a subcategory is called... a subcategory.
How do I create a category and subcategory in HTML?
Use a container element (like <div>) to create the subnav menu and add the subnav links inside it. Wrap a <div> element around the button and the <div> to position the subnav menu correctly with CSS.
How can we save trees in relational database?
- Naive Approach with parent-id:
- Modified Preorder Tree Traversal ( saving a start- & end-point) :
- Saving a path in each Node:
- Closure table.