如何在sql oracle中获取开始日期和结束日期之间的所有年份答案

【问题标题】：How to get all years between a range of begin and end date in sql oracle如何在sql oracle中获取开始日期和结束日期之间的所有年份
【发布时间】：2021-09-19 14:44:21
【问题描述】：

我有一张这样的桌子evaluations

我想通过枚举两个范围之间的所有年份将 bgn_year 和 end_year 转换为 eval_year。结果如下所示：

我尝试通过以下方式连接：

select  employee,
     evaluator_type,
     EVALUATOR,
     (bgn_year-1)+level as eval_year
from evaluations
connect by  (bgn_year-1)+level <=end_year

但我有很多重复的行。我可以添加一个独特的，但我不认为这是这样做的方法。

【问题讨论】：

标签： sql oracle oracle11g

【解决方案1】：

这将是这样的（第 1 - 7 行中的示例数据；您需要的查询从第 8 行开始）：

SQL> with evaluations (employee, bgn_year, end_year, evaluator_type, evaluator)
  2  as
  3  (select 'A', 2019, 2021, 'POS1', 'X' from dual union all
  4   select 'A', 2018, 2021, 'POS2', 'Y' from dual union all
  5   select 'B', 2019, 2020, 'POS1', 'Z' from dual union all
  6   select 'B', 2020, 2021, 'POS1', 'X' from dual
  7  )
  8  select employee,
  9         --
 10         bgn_year + column_value - 1 as eval_year,
 11         --
 12         evaluator_type,
 13         evaluator
 14  from evaluations cross join
 15       table(cast(multiset(select level from dual
 16                           connect by level <= end_year - bgn_year + 1
 17                          ) as sys.odcinumberlist));

EMPLOYEE    EVAL_YEAR EVALUATOR_TYPE  EVALUATOR
---------- ---------- --------------- ----------
A                2019 POS1            X
A                2020 POS1            X
A                2021 POS1            X
A                2018 POS2            Y
A                2019 POS2            Y
A                2020 POS2            Y
A                2021 POS2            Y
B                2019 POS1            Z
B                2020 POS1            Z
B                2020 POS1            X
B                2021 POS1            X

11 rows selected.

SQL>

【讨论】：

【解决方案2】：

以下是使用标准 SQL 递归查询执行此操作的方法：

with cte (employee, bgn_year, end_year, evaluator_type, evaluator, year) as
(
  select employee, bgn_year, end_year, evaluator_type, evaluator, bgn_year from evaluations
  union all
  select employee, bgn_year, end_year, evaluator_type, evaluator, year + 1 from cte
  where year < end_year
)
select employee, year, evaluator_type, evaluator
from cte
order by employee, bgn_year, evaluator_type, evaluator, year;

演示：https://dbfiddle.uk/?rdbms=oracle_18&fiddle=588fdf9b08b7d5ac49ad830c5269eb62

【讨论】：