Return every NMR signal recorded as a dd, with its compound, its shift and its two coupling constants, largest first within the signal. The chain is spectrum → range → signal → coupling, four joins deep, and the two couplings are two rows you have to bring onto one line. Round the shift to three decimals and the couplings to two. Twenty-six signals answer this; 7-Bromo-1H-indole has a dd at 6.649 ppm with J = 3.16 and 2.21 Hz.
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.