A guided tour of querying this database, each step preloaded into the live editor: run it, change it, break it and read the error. Each step is given in SQL and, where it can be expressed, as a Mango query too.
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.