CREATE TABLE performance (songid DECIMAL, bandmate DECIMAL, stageposition TEXT)
CREATE TABLE albums (aid DECIMAL, title TEXT, year DECIMAL, label TEXT, type TEXT)
CREATE TABLE instruments (songid DECIMAL, bandmateid DECIMAL, instrument TEXT)
CREATE TABLE tracklists (albumid DECIMAL, position DECIMAL, songid DECIMAL)
CREATE TABLE vocals (songid DECIMAL, bandmate DECIMAL, type TEXT)
CREATE TABLE band (id DECIMAL, firstname TEXT, lastname TEXT)
CREATE TABLE songs (songid DECIMAL, title TEXT)

What is the most used instrument?
SELECT instrument FROM instruments GROUP BY instrument ORDER BY COUNT(*) DESC LIMIT 1
SELECT "instrument" FROM "instruments" GROUP BY "instrument" ORDER BY COUNT(*) DESC NULLS LAST LIMIT 1