Select within Select in SQL

Question

I'm having a really hard time wrapping my head around using this function and when to use it and the logic behind it.

For instance:
/*Select the code which would show the year when neither a Physics or Chemistry award was given */

I do not understand why it's: Where yr NOT (Select the code which shows the years when a Medicine award was given but no Peace or Literature award was )

AND this query ( /*Select the code which would show the year when neither a Physics or Chemistry award was given */)

...contradicts another question that needs the subjs. separated into two Where clauses.

:( HELP, If you have a site that explains the select clauses in great detail with ample examples I would most appreciate it. This is the biggest thing holding me back in SQL.

Answer 1

Bumping this thread seeing that no replies were given.

https://www.tutorialspoint.com/sql/sql-sub-queries.htm

Answer 2

Try to understand correlated query.. Sub query