When to Use the “ON UPDATE CASCADE” Clause?

When a record in a parent table is updated, it often requires updating related records in child tables to maintain data consistency. Manually updating these child records can be time–consuming and error–likely, especially in large databases with complex relationships. We will understand through the below examples.

Let’s set up an environment

The syntax for using “ON UPDATE CASCADE” is applied when defining a foreign key constraint in the child table. Here is an example:

CREATE TABLE parent_table (
    parent_id INT PRIMARY KEY
);
CREATE TABLE child_table (
    child_id INT PRIMARY KEY,
    parent_id INT,
    FOREIGN KEY (parent_id) REFERENCES parent_table(parent_id) ON UPDATE CASCADE
);

Explanation: The above query creates two tables: parent_tathe le with a primary key parent_id, and child_table with a primary key child_id and a foreign key parent_id referencing the parent_id in parent_table. The ON UPDATE CASCADE clause ensures that if the parent_id in parent_table is updated, the corresponding parent_id in child_table is also updated to maintain referential integrity.

In PL/SQL, managing the update of related records in child tables can be a challenging task especially when dealing with complex data relationships. The “ON UPDATE CASCADE” option provides a powerful solution to automate the update of child records when the corresponding parent record is updated. In this article, We will explore the scenarios where “ON UPDATE CASCADE” is beneficial along with some examples and so on.