Using joins to compare columns by priority among the table. For example, left join returns all values from the first table and null value for the not-matched records from the second table. Similarly, we can use right join, inner join, full join and self join as per our requirements.
Smells like a precursor to SPAM. You copied a paragraph from Example 2 of the article at the following link. Or should I say your spam-testing-bot did?
https://www.geeksforgeeks.org/how-to-compare-columns-in-two-different-tables-in-sql/
--Jeff Moden
Change is inevitable... Change for the better is not.