SQLiteでの年齢計算

/* SQLiteの場合 */
SELECT
    ((julianday('now') - julianday(date)) * 0.00273785) 
FROM 
    birthday; 
 
 
/* MySQLの場合 */
SELECT
    YEAR(DATE_SUB(now(),INTERVAL to_days(date) DAY)) 
FROM 
    birthday; 
 
 
/* PostgreSQLの場合 */
SELECT
    age(date) 
FROM 
    birthday;

CREATE TABLE birthday (
    id          INTEGER NOT NULL,
    date        DATE,
    PRIMARY KEY (id)
);
 
INSERT INTO birthday (date) VALUES (date('now', '-12 years'));
INSERT INTO birthday (date) VALUES (date('now', '-21 years'));
INSERT INTO birthday (date) VALUES (date('now', '-7 years'));
INSERT INTO birthday (date) VALUES (date('now', '-29 years'));
INSERT INTO birthday (date) VALUES (date('now', '-40 years'));
INSERT INTO birthday (date) VALUES (date('now', '-35 years'));
INSERT INTO birthday (date) VALUES (date('now', '-68 years'));
 
INSERT INTO birthday (date) VALUES (date('now', '-12 years', '1 days'));
INSERT INTO birthday (date) VALUES (date('now', '-21 years', '1 days'));
INSERT INTO birthday (date) VALUES (date('now', '-7 years', '1 days'));
INSERT INTO birthday (date) VALUES (date('now', '-29 years', '1 days'));
INSERT INTO birthday (date) VALUES (date('now', '-40 years', '1 days'));
INSERT INTO birthday (date) VALUES (date('now', '-35 years', '1 days'));
INSERT INTO birthday (date) VALUES (date('now', '-68 years', '1 days'));

SELECT 
    id, 
    date, 
    ((julianday('now') - julianday(date)) * 0.00273785) age 
FROM 
    birthday;