Question

我正在尝试创建一个选项，可以获取表格中所有人的姓名和生日，这些人在今天和接下来的4天之间都有生日。

我刚开始使用这个非常硬编码的长代码，理论上可行：

select name, birthday from
  (select name, birthday, to_date('DD-MM-YYYY') as today from user_table)
where (extract(month from(birthday)) = extract(month from(today))
  or extract(month from(birthday)) = extract(month from(today+1))
  or extract(month from(birthday)) = extract(month from(today+2))
  or extract(month from(birthday)) = extract(month from(today+3))
  or extract(month from(birthday)) = extract(month from(today+4)))
and (extract(day from(birthday)) = extract(day from(heute))
  or extract(day from(birthday)) = extract(day from(today+1))
  or extract(day from(birthday)) = extract(day from(today+2))
  or extract(day from(birthday)) = extract(day from(today+3))
  or extract(day from(birthday)) = extract(day from(today+4)))
order by extract(month from(birthday)) asc, extract(day from(birthday)) asc

此查询的问题在于，例如，只要“今天”变量位于该月的最后一天，它也会向人们显示一个月的开始日期。

向我建议的一个解决方案是使用“between”函数，稍微更改此查询：

select name, birthday from
  (select name, birthday, to_date('DD-MM-YYYY') as today from user_table)
where (extract(month from(birthday)) between extract(month from(today)) and extract(month from(today+4)))
and (extract(day from(birthday)) between extract(day from(today)) and extract(day from(today+4)))
order by extract(month from(birthday)) asc, extract(day from(birthday)) asc

虽然当我在“31-12-2017”运行时，每当年或月改变时，我都没有得到任何结果。

我也试过做一些更重的计算，因为试图将当前的“今天”日期带回add_months函数的“birtday”，所以我不必使用任何额外的条件来检查日和月。但它永远不会正确返回日期（在月/年的最后一天的情况下）。这是我做的代码示例：

select name, birthday, add_months(today, -month_difference) as today_minus_difference from
  (select name, birthday, today, floor(months_between(today, birthday)) as month_difference from
    (select name, birthday, to_date('DD-MM-YYYY') as today from table_users)
  )
where birthday between add_months(today, -month_difference) and add_months(today+4, -month_difference)
order by extract(month from(birthday)) asc, extract(day from(birthday)) asc;

between函数中是否缺少某些内容？当它改变数月或数年时，它不能计算between日期吗？或者我错过了逻辑中的其他内容？

编辑：有些人问我是如何处理闰年的，这是我最终的最终查询。我确信它可以改进，但它适用于两种情况（年变化和闰年）。

select name, birthday
from users
  (select to_date(input_date) + rownum - 1 as today from dual connect by level <=5)
where to_char(birthday, 'dd.mm') = to_char(today, 'dd.mm')
union
select name, birthday
from users
  (select to_date(input_date) as today from dual)
where where to_char(birthday, 'dd.mm') = to_char(today, 'dd.mm')
or birthday between (add_months(today, -((extract(year from(today)) - extract(year from(birthday)))*12)))
and (add_months(today+4, -((extract(year from(today)) - extract(year from(geburtstag)))*12)))

按生日订购;

我只使用第一部分并添加“之间”条件，但它不断带来重复结果。我可能已经错过了一些东西，但它仍然适用于Union的这些解决方案。

Answer 1

我猜你选择了一个简单而又简单的方法。明确存在：

select
  name,
  birthdate
from
  user_table,
  (select sysdate + rownum - 1 check_date from dual connect by level <= 5)
where   
  to_char(birthdate, 'dd.mm') = to_char(check_date, 'dd.mm')

年份更改时sysdate出现问题

1 个答案: