D8-leetcode197. 上升的温度(简单)

给定一个 Weather 表，编写一个 SQL 查询，来查找与之前（昨天的）日期相比温度更高的所有日期的 Id。

例如，根据上述给定的 Weather 表格，返回如下 Id:

准备数据：

Create table If Not Exists Weather (Id int, RecordDate date, Temperature int);
insert into Weather (Id, RecordDate, Temperature) values ('1', '2015-01-01', '10');
insert into Weather (Id, RecordDate, Temperature) values ('2', '2015-01-02', '25');
insert into Weather (Id, RecordDate, Temperature) values ('3', '2015-01-03', '20');
insert into Weather (Id, RecordDate, Temperature) values ('4', '2015-01-04', '30');

解决思路：

select * from Weather a 
    inner join Weather b
    on a.Temperature>b.Temperature
    where datediff(a.RecordDate,b.RecordDate)=1;
    

select a.Id from Weather a 
    inner join Weather b
    on a.Temperature>b.Temperature
    where datediff(a.RecordDate,b.RecordDate)=1;

知识点：
两个日期计算天数差
date_diff（time1，time2）：返回两个日期之间（time1-time2）的天数。
eg：
select datediff('2008-08-08','2008-08-01');-- 相差：7 天