从日期范围生成天
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：
天
2010-01-20 2010-01-21 2010-01-22 2010-01-23 2010-01-24
写回答
-
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，其性能令人惊讶地良好：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少量调整。来源：stack overflow
2020-05-08 10:58:34赞同 展开评论 打赏
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