SQL集團按範圍

Question

我們有兩列First_Issue和Expiry_Issue

如果我想了解我有多少用戶，我們有問題1做這樣的查詢：

select COUNT(*) from Subscriber 
where First_issue <= 1 and Expiry_issue >= 1 

現在我想編寫一個查詢，顯示我們每個問題的用戶數量，不確定從哪裏開始，讚賞的指針。

Answer 1

如果你沒有在issues表中可用的所有問題的數字，你可以這樣生成它們：

WITH Issues AS (
    SELECT 1 as Number 
    UNION ALL 
    SELECT Number + 1 as Number 
    FROM Issues WHERE Number + 1 <= (SELECT MAX(Expiry_Issue) FROM Subscriber) 
) 
SELECT issue.Number, COUNT(DISTINCT s.id) 
FROM 
    Subscriber s INNER JOIN 
    Issues i ON i.Number BETWEEN s.First_Issue AND s.Expiry_Issue