Database inheritance is a fundamental concept in database design that allows for the creation of a hierarchy of data structures. This technique is used to organize and manage data in a more efficient and logical manner. In this article, we will explore the different types of database inheritance techniques and how they can be applied in database design.
1. Single Table Inheritance
Single Table Inheritance (STI) is a database inheritance technique where all data from different subclasses are stored in a single table. This approach is simple and efficient, as it avoids the need for multiple tables to store related data. However, it can cause data redundancy and may lead to performance issues when dealing with large datasets.
Let's consider an example of a database for a company that sells different types of products. The company offers both physical and digital products, which have different attributes. Using STI, we can create a single table called "products" that contains all the attributes of both physical and digital products. The "type" attribute can be used to differentiate between the two types of products.
2. Class Table Inheritance
Class Table Inheritance (CTI) is a database inheritance technique where each subclass has its own separate table, and a parent table contains common attributes shared by all subclasses. This approach eliminates data redundancy and allows for more efficient data manipulation. However, it can be complex to implement and may require more joins to retrieve data.
Continuing with our previous example, we can create two separate tables for physical and digital products. These tables will contain specific attributes for each type of product, while the common attributes can be stored in the "products" table.
3. Concrete Table Inheritance
Concrete Table Inheritance (CTI) is a database inheritance technique where each subclass has its own separate table, and there is no parent table. This approach allows for the most flexibility, as each subclass can have its own unique attributes. However, it can be challenging to maintain and may result in a large number of tables.
In our example, we can create separate tables for each type of product, such as "physical_products" and "digital_products." These tables will contain all the attributes specific to each type of product, without a parent table.
4. Shared Primary Key Inheritance
Shared Primary Key Inheritance (SPKI) is a database inheritance technique where the primary key of the parent table is also the primary key of the child table. This approach ensures a one-to-one relationship between the parent and child tables. However, it can be complex to implement and may result in a large number of tables.
For our product database example, we can use SPKI to create a "products" table as the parent table and separate tables for each type of product, such as "physical_products" and "digital_products." These tables will have a primary key that references the primary key of the "products" table.
5. Table Per Type Inheritance
Table Per Type Inheritance (TPT) is a database inheritance technique where each subclass has its own separate table, and there is a parent table that contains common attributes shared by all subclasses. However, unlike CTI, the parent table does not have a primary key. Instead, each child table has a foreign key that references the parent table. This approach eliminates data redundancy and allows for efficient data manipulation.
In our example, we can use TPT to create a parent table called "products" that contains common attributes shared by both physical and digital products. The "physical_products
