Return one row per compound with how many listings it has and how many of those declare a GHS hazard, keeping only compounds where the two numbers differ and the second is not zero. A hazard is a claim a supplier makes, so silence in one listing is not safety — it is a listing that carries the older risk-phrase vocabulary, or none at all. Order by number of listings, then by name. One hundred and eighty-three compounds answer this; Ethanol has two listings and one GHS block.
A advanced exercise, answered in SQL. It is marked by the rows your query returns rather than by how you wrote it, with 3 hints if you want them.
Ask the same question of a chemical dataset in SQL and in Mango and compare the two answers. The database is a SQLite file your browser downloads once and queries locally, so nothing you write ever leaves your machine — which is also why the tool needs JavaScript.