Problem
Table: Weather
+---------------+---------+
| Column Name | Type |
+---------------+---------+
| id | int |
| recordDate | date |
| temperature | int |
+---------------+---------+
id is the primary key for this table.
This table contains information about the temperature on a certain day.
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.
Examples
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
Method 1 - Using where clause
Code
SQL
SELECT q.id AS id FROM Weather p
JOIN Weather q
WHERE q.recordDate = (p.recordDate + 1) AND q.temperature > p.temperature
But above will not work, as we are not using date addition operator correctly. We can do:
SELECT q.id AS id FROM Weather p
JOIN Weather q
WHERE TO_DAYS(q.recordDate) = TO_DAYS(p.recordDate) + 1 AND q.temperature > p.temperature