试下
SELECT number FROM t1 WHERE date BETWEEN '2021-08-01' AND '2021-08-30'
UNION ALL
SELECT number FROM t2 WHERE date BETWEEN '2021-08-01' AND '2021-08-30'
UNION ALL
SELECT number FROM t3 WHERE date BETWEEN '2021-08-01' AND '2021-08-30'
使用”union all“