What is the best way to handle cascading deletes in a relational database design pattern?

1 Use foreign key constraints

Foreign key constraints are a common and effective way to handle cascading deletes in a database. This rule ensures that the values in one column of a table match the values in another column of a related table. To define the action to take when a parent record is deleted, you can use the ON DELETE clause of the foreign key constraint. CASCADE will automatically delete the related records in the child table, SET NULL will set the foreign key column of the related records in the child table to null, SET DEFAULT will set the foreign key column of the related records in the child table to a default value, and NO ACTION will not allow you to delete them if they have orders. Using foreign key constraints with an appropriate ON DELETE action can help maintain data integrity and consistency, but you should also consider performance and business implications when choosing which option is best for your needs.

2 Use triggers

Triggers in your database can be an effective way to handle cascading deletes. A trigger is a piece of code that runs automatically when a certain event occurs in the database, such as inserting, updating, or deleting a record. With triggers, you can perform custom actions when a record is deleted, such as deleting or updating related records in another table. While triggers give you more flexibility and control over the logic and behavior of the cascading deletes, they can be difficult to debug and maintain, affect the performance and scalability of the database, and cause unexpected side effects. Thus, it's important to use triggers with caution and only when foreign key constraints are not sufficient or suitable for your needs.

3 Use application logic

A third way to handle cascading deletes is to use application logic in your code, which gives you the most flexibility and control over the process. However, this can also increase complexity and maintenance of your code, reduce performance and security, and compromise the integrity and consistency of your data. Therefore, you should use application logic only when you have a specific requirement that cannot be met by the database layer, or when you have a clear strategy for implementing and testing the cascading deletes.

4 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?