leetcode-solution/SQL/Q197RisingTemperature.sql at main · b-knd/leetcode-solution · GitHub

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/*
197. Rising Temperature

Description:
Write an SQL query to find all dates' Id with higher temperatures compared to its previous dates (yesterday).

Return the result table in any order.

The query result format is in the following example.


Example 1:

Input:
Weather table:
+----+------------+-------------+
| id | recordDate | temperature |
+----+------------+-------------+
| 1  | 2015-01-01 | 10          |
| 2  | 2015-01-02 | 25          |
| 3  | 2015-01-03 | 20          |
| 4  | 2015-01-04 | 30          |
+----+------------+-------------+
Output:
+----+
| id |
+----+
| 2  |
| 4  |
+----+
Explanation:
In 2015-01-02, the temperature was higher than the previous day (10 -> 25).
In 2015-01-04, the temperature was higher than the previous day (20 -> 30).
*/

/* Solution */
select id from Weather w where w.temperature >
(select temperature from weather w2 where w2.recordDate = w.recordDate - INTERVAL 1 Day);

/* use a nested select to obtain temperature a day before by utilising "INTERVAL 1 Day" */