sql获取两个表日期之间的所有日期

Question

另一个 SQL 挑战！

我想编写一个 MySQL 查询，在一条记录中获取两个日期之间的所有天数。

opening_times

id   | begin      | end
1    | 10:00:00   | 17:00:00
2    | 10:00:00   | 18:00:00
3    | 10:00:00   | 19:00:00

opening_periods

id   | opening_time_id  | begin       | end         
1    | 3                | 2016-03-26  | 2016-03-28
2    | 2                | 2016-03-29  | 2016-04-01  
3    | 1                | 2016-04-02  | 2016-04-03  

我想要这个输出：

date        | begin    | end
2016-03-26  | 10:00:00 | 19:00:00
2016-03-27  | 10:00:00 | 19:00:00
2016-03-28  | 10:00:00 | 19:00:00
2016-03-29  | 10:00:00 | 18:00:00
2016-03-30  | 10:00:00 | 18:00:00
2016-03-31  | 10:00:00 | 18:00:00
2016-04-01  | 10:00:00 | 18:00:00
2016-04-02  | 10:00:00 | 17:00:00
2016-04-03  | 10:00:00 | 17:00:00

我应该为此使用子查询吗？ 感谢您为我指明了正确的方向！

Answer 1

你可以在 mysql 中通过复杂的查询来解决它。 首先，您需要构建一个将生成整数序列的子查询，如this answer：

SELECT @row := @row + 1 as rown FROM 
(select 0 union all select 1 union all select 3 union all select 4 union all select 5 union all select 6 union all select 6 union all select 7 union all select 8 union all select 9) t1,
(select 0 union all select 1 union all select 3 union all select 4 union all select 5 union all select 6 union all select 6 union all select 7 union all select 8 union all select 9) t2, 
(select 0 union all select 1 union all select 3 union all select 4 union all select 5 union all select 6 union all select 6 union all select 7 union all select 8 union all select 9) t3, 
(SELECT @row:=-1) x

这将用于为每个条目生成与日期间隔中的天数一样多的行。

SELECT DATEDIFF(`end`,`begin`) as number_of_days FROM `opening_periods`

所有放在一起看起来像这样：

SELECT DATE_ADD( o.`begin`, INTERVAL days day) as date_field, t.begin, t.end
FROM `opening_periods` o INNER JOIN (
SELECT id, rown as days
FROM `opening_periods`, 
(SELECT @row := @row + 1 as rown FROM 
(select 0 union all select 1 union all select 3 union all select 4 union all select 5 union all select 6 union all select 6 union all select 7 union all select 8 union all select 9) t1,
(select 0 union all select 1 union all select 3 union all select 4 union all select 5 union all select 6 union all select 6 union all select 7 union all select 8 union all select 9) t2, 
(select 0 union all select 1 union all select 3 union all select 4 union all select 5 union all select 6 union all select 6 union all select 7 union all select 8 union all select 9) t3, 
(SELECT @row:=-1) x) numbers_table
WHERE rown <= DATEDIFF(`end`,`begin`)) r
ON o.id = r.id
INNER JOIN `opening_times` t ON o.`opening_time_id` = t.id
ORDER BY o.id

这是一个小提琴：http://rextester.com/AKDRI84101