Calculate Time Duration

-- Create table called dead_adventurers
CREATE TABLE dead_adventurers (
    -- string variable
    name varchar(255),
    -- string variable
    race varchar(255),
    -- string variable
    weapon varchar(255),
    -- date variable
    started_adventure date,
    -- date variable
    died date
)

-- Insert into the table dead_adventurers
INSERT INTO dead_adventurers (name, race, weapon, started_adventure, died)
VALUES ('Fjoak Doom-Wife', 'Human', 'Axe', '09-JAN-2017', '10-Nov-2017'),
       ('Alooneric Cortte', 'Elf', 'Bow', '10-JAN-2017', '11-JAN-2017'),
       ('Piperel Ramsay', 'Elf', 'Sword', '11-JAN-2017', '12-APR-2017'),
       ('Casimir Yardley', 'Elf', 'Magic', '23-JAN-2017', '06-MAY-2017')

-- Get all the columns, and add a new column called days_on_adventure
-- that is the number of days between the start of the adventurer and when they died
SELECT *, died - started_adventure AS days_on_adventure FROM dead_adventurers