展开日期列雪花

Question

我有两个这样的日期列：

date_col_1     date_col_2
2020-02-01     2023-01-01   
2020-03-01     2023-02-01
2020-04-01     .
.              .
.              .
.              .
2022-12-01     2023-12-01

我想要的是每当 date_col_2 > max(date_col_1) 时，所有大于 max(date_col_1) 的值都应该在 [=19= 的最后一个值之下] 像这样，

date_col_1     
2020-02-01      
2020-03-01     
2020-04-01     
.              
.              
.              
2022-12-01
Append here
2023-01-01
2023-02-01
2023-03-01
.
.
.

我试过各种方法，都没有得到想要的结果。 TIA

Answer 1

WITH fake_data AS (
    SELECT 
        TO_DATE(date_col_1,'yyyy-mm-dd') as date_col_1
        ,TO_DATE(date_col_2,'yyyy-mm-dd') as date_col_2
    FROM VALUES
        ('2020-02-01','2023-01-01'),  
        ('2020-03-01','2023-02-01'),
        ('2022-12-01','2023-12-01')
        v(date_col_1, date_col_2)
), massive_date_set as (
    SELECT 
        dateadd('day', row_number()over(order by null), TO_DATE('2000-01-01','yyyy-mm-dd')) AS date
    FROM TABLE(GENERATOR(ROWCOUNT => 356 * 30))
), min_max AS (
    SELECT 
        min(date_col_1) AS date_from
        ,greatest(max(date_col_1), max(date_col_2)) AS date_to
    FROM fake_data
)
SELECT d.date
FROM  min_max AS mm
JOIN massive_date_set d
    ON d.date BETWEEN mm.date_from AND mm.date_to
ORDER BY 1;

给出：

DATE
2020-02-01
2020-02-02
2020-02-03
2020-02-04
2020-02-05
massive cut
2023-11-28
2023-11-29
2023-11-30
2023-12-01

展开日期列雪花

Expand Date Column snowflake

sql

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