DROP DATABASE IF EXISTS quan_test;
CREATE DATABASE quan_test;
use quan_test;

create table t1 (
dt datetime not null,
primary key (dt)
);

create view v3 as select null union all select null union all select null;
create view v10 as select null from v3 a, v3 b union all select null;
create view v1000 as select null from v10 a, v10 b, v10 c;
set @n = 0;
insert into t1 select now()-interval @n:=@n+1 second from v1000 a,v1000 b;


SELECT dt FROM t1 WHERE dt BETWEEN now() - INTERVAL 9 DAY AND now();
SELECT dt FROM t1 WHERE dt BETWEEN now() - INTERVAL 2 DAY AND now();

SELECT a.dt FROM t1 AS a JOIN t1 AS b  ON a.dt=b.dt  WHERE  a.dt BETWEEN now() - INTERVAL 30 MINUTE  AND now();

ALTER TABLE t1 DROP PRIMARy KEY;
ALTER TABLE t1 ADD COLUMN id INT auto_increment PRIMARY KEY FIRST;