# 197. Rising Temperature

> Nguồn: https://tiennhm.io.vn/en/docs/leetcode/database/197-rising-temperature
> Find all dates' `Id` with higher temperatures compared to its previous dates (yesterday).

## Giới thiệu bài toán

Chi tiết: https://leetcode.com/problems/rising-temperature/

Table: `Weather`

| Column Name   | Type    |
| ------------- | ------- |
| id            | int     |
| recordDate    | date    |
| temperature   | int     |

- In SQL, id is the primary key for this table.
- This table contains information about the temperature on a certain day.

> **Tip: Yêu cầu**
>
> Find all dates' `Id` with higher temperatures compared to its previous dates (yesterday).
>
> Return the result table in any order. The 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).

## Giải quyết bài toán

```sql
SELECT w1.id
FROM Weather w1 JOIN Weather w2
    ON w1.RecordDate = DATE_ADD(w2.RecordDate, INTERVAL 1 DAY)
WHERE w1.temperature > w2.temperature;
```

Tham khảo: https://leetcode.com/submissions/detail/1039224990/