Breakdown of Heirarchial queries and building these using different techniques
Source : https://www.linkedin.com/pulse/step-by-step-guide-creating-sql-hierarchical-queries-bibhas-mitra 1. Introduction Hierarchical query is a type of SQL query that is commonly leveraged to produce meaningful results from hierarchical data. Hierarchical data is defined as a set of data items that are related to each other by hierarchical relationships. Hierarchical relationships exist where one item of data is the parent of another item. The real-life examples of the hierarchical data that are commonly stored in databases include the following: Employee hierarchy (employee-manager relationship) Organizational hierarchy Graph of links between web pages Connected social networking graph A set of tasks in a project File system Unless your database is a hierarchical database like IBM Information Management System (IMS), you will need to write hierarchical SQL to retrieve relational data in hierarchical format that establishes parent-child relationships between entities ...