CREATE TABLE table_204_394 (id NUMBER, "year" NUMBER, "album" CLOB, "label" CLOB, "peak chart\ positions\ us" NUMBER, "peak chart\ positions\ us r&b" NUMBER)

how long is the period between the first and last album in the table ?
SELECT MAX("year") - MIN("year") FROM table_204_394
SELECT MAX("year") - MIN("year") FROM "table_204_394"