197. Rising Temperature

Description

SQL Schema

Given a Weather table, write a SQL query to find all dates' Ids with higher temperature compared to its previous (yesterday's) dates. 

+---------+------------------+------------------+
| 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 |
+---------+------------------+------------------+

For example, return the following Ids for the above Weather table: 

+----+
| Id |
+----+
|  2 |
|  4 |
+----+

My Solution

Source Code

1
2
3
4
5

SELECT w1.Id AS 'Id'
FROM Weather AS w1, Weather AS W2
WHERE DATEDIFF(day, w2.RecordDate, w1.RecordDate) = 1 
AND
w1.Temperature > w2.Temperature

Analysis

All we're doing here is using DATEDIFF() to determine which dates are consecutive.