我的WHERE子句（SQL）

Question

我試圖寫一個返回下面列的查詢問題：

owner_id, 
number_of_concluded_bookings, 
number_of_declined_bookings, 
number_of_inquiries 

然而，問題是，我的WHERE子句攪亂查詢，因爲我查詢同一張桌子。這裏是代碼：

SELECT owner_id, 
Count(*) AS number_of_cancelled_bookings 
FROM bookings 
WHERE state IN ('cancelled') 
GROUP BY owner_id 
ORDER BY 1; 

很容易單獨檢索列，但我希望所有這些。假設我想要number_of_concluded_bookings以及那將意味着我將不得不改變WHERE子句...

幫助非常感謝！

Answer 1

考慮有條件聚集：

SELECT owner_id, 
     SUM(CASE WHEN state='concluded' THEN 1 ELSE 0 END) AS number_of_concluded_bookings, 
     SUM(CASE WHEN state='cancelled' THEN 1 ELSE 0 END) AS number_of_cancelled_bookings, 
     SUM(CASE WHEN state='declined' THEN 1 ELSE 0 END) AS number_of_declined_bookings, 
     SUM(CASE WHEN state='inquiries' THEN 1 ELSE 0 END) AS number_of_inquiries 
FROM bookings 
GROUP BY owner_id