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
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