连续增长查询
表有3列: pigid, day, weight,记录每头猪每天的体重变化。我想用一个select语句,查出指定日期(比如今天)之前n天体重连续增加的pigid和day。如果用c语言做循环,用数组weight[pigid][day]来比较,很容易做,但数据量大的时候,要以数组方式保存数据很麻烦。所以想用一条select语句能查出结果。请问如何实现?
CREATE TABLE `pigweight` (
`pigId` varchar(10) DEFAULT NULL,
`day` date DEFAULT NULL,
`weight` float(255,0) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
INSERT INTO `pigweight`(`pigId`, `day`, `weight`) VALUES ('p1', '2018-01-01', 22), ('p1', '2018-01-02', 23), ('p1', '2018-01-03', 24), ('p1', '2018-01-04', 25), ('p1', '2018-01-05', 23), ('p2', '2018-01-01', 32), ('p2', '2018-01-02', 33), ('p2', '2018-01-03', 34), ('p2', '2018-01-04', 30);