What is the difference between left join and right join?

Answer 1

INNER JOIN gets all records that are common between both tables based on the foreign key

LEFT JOIN gets all records from the LEFT linked table but if you have selected some columns from the RIGHT table, if there is no related records, these columns will contain NULL

RIGHT JOIN is like the above but gets all records in the RIGHT table

FULL JOIN gets all records from both tables and puts NULL in the columns where related records do not exist in the opposite table

Reading this article will help you alot: https://www.codeproject.com/Articles/33052/Visual-Representation-of-SQL-Joins

Answer 2

a left join b == b right join a.