How to find child records in oracle

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To find child records in Oracle, you can use the hierarchical query feature provided by Oracle’s SQL language. This feature allows you to retrieve parent-child relationships based on a table’s hierarchical structure.

Example:

Let’s assume you have a table called “employees” with the following structure:

    
      CREATE TABLE employees (
        id NUMBER PRIMARY KEY,
        name VARCHAR2(100) NOT NULL,
        parent_id NUMBER,
        CONSTRAINT fk_parent FOREIGN KEY (parent_id) REFERENCES employees(id)
      );

In this example, the “employees” table has a self-referencing foreign key column called “parent_id” that establishes the parent-child relationship. The “parent_id” column refers to the “id” column of the same table.

Now, let’s say you want to find all the child records of a specific employee with an “id” value of 1. You can use the CONNECT BY clause in Oracle’s SQL to achieve this:

    
      SELECT id, name
      FROM employees
      START WITH id = 1
      CONNECT BY PRIOR id = parent_id;

This query will retrieve all the child records of the employee with an “id” value of 1, including the employee with the “id” value of 1 itself.

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