All About SQL Joins

I was recently asked in an interview to explain the difference between a JOIN and a LEFT JOIN in SQL. Admittedly it had been a while since I had thought about the different SQL joins and I fumbled a little with my answer. So I am taking this opportunity to dive into SQL joins.

What is a SQL join?

A SQL join is a way to combine rows from two or more tables based on a common column between them.

• Let’s break that down using a book and author example where authors can have many books, and a book belongs to an author.

The authors table has an id primary key, name, and age: