Question

我有以下情况：

+------------+-----------+------------+----------------+
| date       | event     | start_date | duration(days) |
+------------+-----------+------------+----------------+
| 2010-01-01 | concert   | 2010-01-01 | 2              |
+------------+-----------+------------+----------------+
| 2010-01-02 | NULL      | NULL       | NULL           |
+------------+-----------+------------+----------------+
| 2010-01-03 | workshops | 2010-01-03 | 3              |
+------------+-----------+------------+----------------+
| 2010-01-04 | NULL      | NULL       | NULL           |
+------------+-----------+------------+----------------+
| 2010-01-05 | NULL      | NULL       | NULL           |
+------------+-----------+------------+----------------+
| 2010-01-06 | NULL      | NULL       | NULL           |
+------------+-----------+------------+----------------+
| 2010-01-07 | NULL      | NULL       | NULL           |
+------------+-----------+------------+----------------+
| 2010-01-08 | festival  | 2010-01-08 | 5              |
+------------+-----------+------------+----------------+
| 2010-01-09 | NULL      | NULL       | NULL           |
+------------+-----------+------------+----------------+

现在，我需要以特定事件发生时每个日期行的方式显示上述信息，其名称显示在事件列中，而不仅仅是在它开始的第一天。

有三个表，一个只有 DATES ，一个有 EVENTS ，另一个有 START_DATES 和 DURATION 每个事件。

到目前为止，我只能生成一个像上面这样的表，但我不知道如何在事件持续时间的每一天用事件名替换NULL值。

SELECT d AS date, event, start_date, duration 
FROM dates 
LEFT JOIN info ON info.start_date=d.date AND city='LA' 
LEFT JOIN events ON events.event=info.event 
WHERE d BETWEEN '2010-01-01' AND '2010-01-09'

有什么想法吗？

Answer 1

下面 - 创建了一个子查询，显示所有事件的开始日期和结束日期，然后加入完整的日期列表：

SELECT d.date, t.event, t.start_date, t.end_date
FROM dates d
LEFT JOIN (SELECT e.event, i.start_date, i.start_date + INTERVAL i.duration DAY AS end_date
            FROM events e
            JOIN info i
                ON e.event = i.event
            WHERE i.city = 'LA'
            ) t
    ON d.date BETWEEN t.start_date AND t.end_date
WHERE d.date BETWEEN '2010-01-01' AND '2010-01-09'
ORDER BY d.date, e.event_name;

如何显示与日期范围

1 个答案: