What's the importance of using a self join in SQL queries?

Question

Self join in sql queries

Answer 1

Kris O. Ouko

It is useful for querying hierarchical data or comparing rows within the same table. A self join uses the innerjoin or left join clause. Because the query that uses self join references the same table, the table alias is used to assign different names to the table within the query.

source:
http://www.sqlservertutorial.net/sql-server-basics/sql-server-self-join/

I hope I was helpful