1.
SELECT
COUNT(CASE WHEN hanbai_tanka <= 1000 THEN hanbai_tanka ELSE NULL END) AS low_price,
COUNT(CASE WHEN hanbai_tanka BETWEEN 1001 AND 3000 THEN hanbai_tanka ELSE NULL END) AS mid_price,
COUNT(CASE WHEN hanbai_tanka >= 3001 THEN hanbai_tanka ELSE NULL END) AS high_price
FROM Shohin;
2.
SELECT
SUM(CASE WHEN hanbai_tanka <= 1000 THEN 1 ELSE 0 END) AS low_price,
SUM(CASE WHEN hanbai_tanka BETWEEN 1001 AND 3000 THEN 1 ELSE 0 END) AS mid_price,
SUM(CASE WHEN hanbai_tanka >= 3001 THEN 1 ELSE 0 END) AS high_price
FROM Shohin;
結果都是正確的
uj5u.com熱心網友回復：
感覺沒啥太大區別啊，你可以比較下兩種方法的執行效率uj5u.com熱心網友回復：
1=1當然正確了，不是推薦用哪個，而是應該用哪個uj5u.com熱心網友回復：
樓上說的對。。轉載請註明出處，本文鏈接：https://www.uj5u.com/shujuku/73678.html
標籤：PostgreSQL
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