Add SQL query for rising temperature comparison

[aryaman0406]

PR Title Format: 197.Rising Temperature.sql

💡 Intuition
The goal is to find records where the temperature today is higher than the temperature yesterday. This inherently requires comparing two different rows from the same Weather table. The key is to correctly link 'today's' record with 'yesterday's' record, which can be done based on the recordDate where today's date is exactly one day after yesterday's date.

✍️ Approach
Self-Join: Join the Weather table with itself (a self-join) to compare different rows. I'll use aliases: today for the current day's record and yesterday for the previous day's record.

Date Comparison: The join condition must ensure that yesterday.recordDate is one day before today.recordDate. The DATEDIFF(today.recordDate, yesterday.recordDate) = 1 function/expression precisely achieves this, as it calculates the difference in days between the two dates.

Temperature Comparison: Apply a WHERE clause to filter the joined records, keeping only those where today.temperature is greater than yesterday.temperature.

Selection: Finally, select the id from the today alias, as the problem asks for the ID of the day with the higher temperature.

Code Solution (SQL)
SQL

SELECT today.id
FROM Weather yesterday
CROSS JOIN Weather today -- Using JOIN here is more standard, but CROSS JOIN works as the condition is in WHERE.

WHERE DATEDIFF(today.recordDate, yesterday.recordDate) = 1
AND today.temperature > yesterday.temperature
;
🔗 Related Issues
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