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Leetcode-Solutions/MySQL/ads-performance.sql at main · rezzcode/Leetcode-Solutions · GitHub

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# Time: O(nlogn)

# Space: O(n)

SELECT ad_id,

CASE

WHEN clicks + views = 0 THEN 0

ELSE ROUND(100 * clicks / (clicks + views), 2)

END ctr

FROM

(SELECT ad_id,

SUM(CASE

WHEN action ='Viewed' THEN 1

ELSE 0

END) views,

SUM(CASE

WHEN action = 'Clicked' THEN 1

ELSE 0

END) clicks

FROM Ads

GROUP BY ad_id) a

ORDER BY ctr DESC,

ad_id ASC