基於起始時間和結束時間的資料進行小時計數

Question

在表格中，資料以時間戳記格式存在，但我以時間（start_at）和時間（end_at）的格式共享它。

表格結構：

id, start_at, end_at
1, 03:00:00, 06:00:00
2, 02:00:00, 05:00:00
3, 01:00:00, 08:00:00
4, 08:00:00, 13:00:00
5, 09:00:00, 21:00:00
6, 13:00:00, 16:00:00
6, 15:00:00, 19:00:00

對於結果，我們需要計算在start_at和end_at時間之間活動的id數量。

hours, count
0, 0
1, 1
2, 2
3, 3
4, 3
5, 2
6, 1
7, 1
8, 1
9, 2
10, 2
11, 2
12, 2
13, 3
14, 2
15, 3
16, 2
17, 2
18, 2
19, 1
20, 1
21, 0
22, 0
23, 0

Answer 1

要么

WITH RECURSIVE
cte AS (
    SELECT 0 `hour`
    UNION ALL
    SELECT `hour` + 1 FROM cte WHERE `hour` < 23
)
SELECT cte.`hour`, COUNT(test.id) `count`
FROM cte 
LEFT JOIN test ON cte.`hour` >= HOUR(test.start_at)
              AND cte.`hour` < HOUR(test.end_at)
GROUP BY 1
ORDER BY 1;

要么

WITH RECURSIVE
cte AS (
    SELECT CAST('00:00:00' AS TIME) `hour`
    UNION ALL
    SELECT `hour` + INTERVAL 1 HOUR FROM cte WHERE `hour` < '23:00:00'
)
SELECT cte.`hour`, COUNT(test.id) `count`
FROM cte 
LEFT JOIN test ON cte.`hour` >= test.start_at 
              AND cte.`hour` < test.end_at 
GROUP BY 1
ORDER BY 1;

第一個查詢以時間格式傳回小時列，而第二個查詢以數值形式傳回此列。選擇對您來說安全的變體。

https://dbfiddle.uk/?rdbms=mysql_8.0&fiddle=5a77b6e3158be06c7a551cb7e64673de

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