My solutions of the exercises from the SQL Zoo tutorials.
- SELECT within SELECT problems (https://sqlzoo.net/wiki/SELECT_within_SELECT_Tutorial)
- SUM and COUNT problems (https://sqlzoo.net/wiki/SUM_and_COUNT)
- SELECT from WORLD (https://sqlzoo.net/wiki/SELECT_from_WORLD_Tutorial)
- SELECT from NOBEL (https://sqlzoo.net/wiki/SELECT_from_Nobel_Tutorial)