如何使用 SQL 查询生成此数据列表？

Question

年	月
2021	1
2021	2
2021	3
2021	4
2021	5
2021	6
2021	7
2021	8
2021	9
2021	10
2021	11
2021	12
2022	1
2022	2
2022	3
2022	4
2022	5
2022	6
2022	7
2022	8
2022	9
2022	10
2022	11
2022	12

我可以得到一列，例如
SELECT * FROM generate_series(1,12) as month 但我找不到如何在它旁边生成另一列，而不是加入实际的 table.

Answer 1

您可以使用交叉连接：

SELECT y.year, m.month
FROM (SELECT 2020 + generate_series(1, 2) AS year) y
CROSS JOIN (SELECT generate_series(1, 12) AS month) m
ORDER BY y.year, m.month;

Demo

Answer 2

每个月创建一个日期列表：

select extract(year from dt) as "year",
       extract(month from dt) as "month"
from generate_series(date '2021-01-01', 
                     date '2022-12-31', 
                     interval '1 month') as g(dt)
order by g.dt;

Answer 3

select
    extract(year from d) "year", 
    extract(month from d) "month"
from generate_series ('2021-01-01', '2022-12-01', interval '1 month') as d;

Answer 4

您可以使用 CASE 语句

Select year.*,
   CASE 
       WHEN year = 2021 THEN generate_series(1,12)
       WHEN year = 2022 THEN generate_series(1,12)
   END as month
from generate_series(2021,2022) as year

Answer 5

使用整数运算

select 2021 + m / 12 "year", m % 12 + 1 "month"
from generate_series(0, 23) as m

如何使用 SQL 查询生成此数据列表？

how can I generate this list of data with a SQL query?

sql

postgresql

subquery

Demo