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While this exact problem may not always appear, similar SQL interview questions about grouped maximum values and earliest occurrences are common. Companies often test candidates on aggregation, filtering, and window function usage.
The common approach is to first compute the maximum degree for each city using GROUP BY with MAX(). Then filter rows matching that maximum and select the earliest date using MIN() or a window function. This ensures you return the first day the highest temperature occurred.
Conceptually, the problem relies on grouped aggregation, which is similar to grouping data by keys like a hash map. SQL handles this internally using GROUP BY to compute statistics such as maximum values for each city.
Useful SQL techniques include aggregation with GROUP BY, subqueries or joins, and window functions like ROW_NUMBER() or RANK(). These help identify maximum values per group and select the earliest matching record efficiently.