PHP-SQL查询上升的温度
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。
+---------+------------------+------------------+
| Id(INT) | RecordDate(DATE) | Temperature(INT) |
+---------+------------------+------------------+
| 1 | 2015-01-01 | 10 |
| 2 | 2015-01-02 | 25 |
| 3 | 2015-01-03 | 20 |
| 4 | 2015-01-04 | 30 |
+---------+------------------+------------------+
例如,根据上述给定的 Weather 表格,返回如下 Id:
+----+
| Id |
+----+
| 2 |
| 4 |
+----+
来源:力扣(LeetCode)
子查询
SELECT
Id
FROM
Weather as a
where Temperature > (select Temperature from Weather as w where DATEDIFF(a.RecordDate, w.RecordDate) = 1
AND a.Temperature > w.Temperature) order by a.RecordDate desc
JOIN查询
SELECT
weather.id AS 'Id'
FROM
weather
JOIN
weather w ON DATEDIFF(weather.RecordDate, w.RecordDate) = 1
AND weather.Temperature > w.Temperature
执行时间可以看出 JOIN查询优于 子查询