从日期范围生成天数

Question

我想运行一个查询

select ... as days where `date` is between '2010-01-20' and '2010-01-24'

并返回如下数据：

days
----------
2010-01-20
2010-01-21
2010-01-22
2010-01-23
2010-01-24

Answer 1

此解决方案不使用 循环，过程或临时表 。子查询会生成最近10,000天的日期，并且可以扩展为任意向前或向后的日期。

select a.Date 
from (
    select curdate() - INTERVAL (a.a + (10 * b.a) + (100 * c.a) + (1000 * d.a) ) DAY as Date
    from (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as a
    cross join (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as b
    cross join (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as c
    cross join (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as d
) a
where a.Date between '2010-01-20' and '2010-01-24'

输出：

Date
----------
2010-01-24
2010-01-23
2010-01-22
2010-01-21
2010-01-20

性能说明

在这里对其进行测试，其性能出奇地好：
上面的查询花费了0.0009秒。

如果我们扩展子查询以生成近似值。100,000个数字（因此约有274年的日期），运行时间为0.0458秒。

顺便说一句，这是一种非常可移植的技术，该技术可以在大多数数据库中进行细微调整。

SQL Fiddle示例返回1,000天