Question

我在SQL表中有以下数据：

+------------------------------------+
| ID          YEARS       START_DATE |
+------------------------------------+
| ----------- ----------- ---------- |
| 1           5           2020-12-01 |
| 2           8           2020-12-01 |
+------------------------------------+

尝试创建一个SQL，以扩展上述数据，并根据上表中的YEARS和START_DATE给出每年的开始和结束日期。示例输出如下：

+-----------------------------------------------+
|  ID          YEAR        DATE_START DATE_END  |
+-----------------------------------------------+
| ----------- ----------- ---------- ---------- |
| 1           1           2020-12-01 2021-11-30 |
| 1           2           2021-12-01 2022-11-30 |
| 1           3           2022-12-01 2023-11-30 |
| 1           4           2023-12-01 2024-11-30 |
| 1           5           2024-12-01 2025-11-30 |
| 2           1           2020-12-01 2021-11-30 |
| 2           2           2021-12-01 2022-11-30 |
| 2           3           2022-12-01 2023-11-30 |
| 2           4           2023-12-01 2024-11-30 |
| 2           5           2024-12-01 2025-11-30 |
| 2           6           2025-12-01 2026-11-30 |
| 2           7           2026-12-01 2027-11-30 |
| 2           8           2027-12-01 2028-11-30 |
+-----------------------------------------------+

Answer 1

为此，我将使用内联计数，因为它们比递归CTE解决方案快得多。假设您的Years值较低：

WITH YourTable AS(
    SELECT *
    FROM (VALUES(1,5,CONVERT(date,'20201201')),
                (2,8,CONVERT(date,'20201201')))V(ID,Years, StartDate))
SELECT ID,
       V.I + 1 AS [Year],
       DATEADD(YEAR, V.I, YT.StartDate) AS StartDate,
       DATEADD(DAY, -1, DATEADD(YEAR, V.I+1, YT.StartDate)) AS EndDate
FROM YourTable YT
     JOIN (VALUES(0),(1),(2),(3),(4),(5),(6),(7),(8),(9),(10))V(I) ON YT.Years > V.I;

如果您有10多年以上的经验，则可以使用创建统计表或在CTE中创建大型内联表。开头为：

WITH N AS(
    SELECT N
    FROM (VALUES(NULL),(NULL),(NULL),(NULL),(NULL),(NULL),(NULL),(NULL),(NULL),(NULL))N(N)),
Tally AS(
    SELECT ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) -1 AS I --remove the -1 if you don't want to start from 0
    FROM N N1, N N2) --100 rows, add more Ns for more rows
...

当然，我怀疑您拥有1000年的数据。

Answer 2

您可以使用递归CTE：

with cte as (
      select id, 1 as year, start_date,
             dateadd(day, -1, dateadd(year, 1, start_date)) as end_date,
             years as num_years
      from t
      union all
      select id, year + 1, dateadd(year, 1, start_date),
             dateadd(day, -1, dateadd(year, 1, start_date)) as end_date,
             num_years             
      from cte
      where year < num_years
     )
select id, year, start_date, end_date
from cte;

Here是db <>小提琴。

Answer 3

在查询中，您可以使用以下内容：

DATEADD(YEAR, 1, DATE_START) - 1

要将其添加到表中，您只需创建额外的列，并将其设置为与上面的值相等，例如

UPDATE MyTable
SET DATE_END = DATEADD(YEAR, 1, DATE_START) - 1

Answer 4

如果您使用的是SQL Server，则可以尝试将operator CROSS APPLY与 master.dbo.spt_values 表一起使用以获取数字列表并生成日期：

 select ID,T.number+1 as YEAR, 
 --generate date_start using T.number
 dateadd(year,T.number,START_DATE)date_start,
 --generate end_date: adding 1 year to start date  
 dateadd(dd,-1,dateadd(year,1,dateadd(year,T.number,START_DATE)))date_end 
 from Table
 cross apply
 master.dbo.spt_values T
 where T.type='P' and T.number<YEARS

SQL在给定开始日期和年数的情况下获取每年的开始和结束日期的行

4 个答案: