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

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 FETCH FIRST 1 ROWS ONLY