我有一個人名單，我必須顯示男性和女性條目的數量。
SELECT COUNT(gender)
FROM people a
JOIN accounts b
ON b.idpers = a.idpers
JOIN cards c
ON c.nrc = b.nrc
WHERE c.category = 'CREDIT'
AND a.gender = :gender
我已經嘗試過這個并且它有效，但我希望它在沒有提示輸入的情況下同時顯示男性和女性的數量。有任何想法嗎？
uj5u.com熱心網友回復：
您可以按以下方式對查詢進行分組gender：
SELECT gender, COUNT(*)
FROM people a
JOIN accounts b ON b.idpers = a.idpers
JOIN cards c ON c.nrc = b.nrc
WHERE c.category= 'CREDIT'
GROUP BY gender
uj5u.com熱心網友回復：
您可以使用條件聚合，例如
SELECT SUM(CASE WHEN gender = 'male' THEN 1 END) AS count_male,
SUM(CASE WHEN gender = 'female' THEN 1 END) AS count_female
FROM people p
JOIN accounts a
ON a.idpers = p.idpers
JOIN cards c
ON c.nrc = a.nrc
WHERE c.category = 'CREDIT'
在同一行顯示兩個計數
uj5u.com熱心網友回復：
您可以按性別按組執行此操作。這是你如何做到這一點
SELECT gender,COUNT(gender)
FROM people a
JOIN accounts b ON b.idpers=a.idpers
JOIN cards c ON c.nrc=b.nrc
WHERE c.category= 'CREDIT' group by gender;
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