雪花 - 给定开始日期和结束日期列，分解每个月并将该月的天数计算到单独的行中

Question

我有下面的 table (dates_table)，其中的行如下所示，例如 start_date = '2022-01-25' 和 end_date = '2022-02-04'.

start_date	end_date
2022-01-25	2022-02-04
2018-08-31	2018-10-05

我正在尝试从上面创建一个新的 table 并添加另一列 days_count，这需要 start_date 1/25，看看有多少天那个月（第一行是 7，因为 1/25、1/26、1/27、1/28、1/29、1/30、1/31），下一行是 4，因为 2/1 是 4 天- 2/4:

month	start_date	end_date	days_count
2022-01-01	2022-01-25	2022-02-04	7
2022-02-01	2022-01-25	2022-02-04	4
2018-08-01	2018-08-31	2018-10-05	1
2018-09-01	2018-08-31	2018-10-05	30
2018-10-01	2018-08-31	2018-10-05	5

Answer 1

您应该添加另一列来指示您正在计算的计数类型，但您可以使用 datediff、last_day 和 date_trunc（首先获取月）。这是一个例子

set start_date='2022-01-25'::date;
set end_date='2022-02-04'::date;

select $start_date,
       $end_date,
       'Start_Remainder' as label,
       datediff(day,$start_date,last_day($start_date))+1 as days_count
union all
select $start_date,
       $end_date,
       'End_Accrued' as label,
       datediff(day,date_trunc('month',$end_date),$end_date)+1 as days_count

如果我是你，我会在单独的列中显示计数

select $start_date,
       $end_date,
       datediff(day,$start_date,last_day($start_date))+1 as Start_Remainder_Days,
       datediff(day,date_trunc('month',$end_date),$end_date)+1 as End_Accrued_Days

Answer 2

有一个 CTE 提供数据，还有几个 pre-conditioning CTE

WITH data_table(start_date, end_date) as (
    SELECT * from values
        ('2022-01-25'::date, '2022-02-04'::date),
        ('2018-08-31'::date, '2018-10-05'::date)
), large_range as (
    SELECT row_number() over (order by null)-1 as rn
    FROM table(generator(ROWCOUNT => 1000))
), pre_condition as (
    SELECT 
        start_date
        ,end_date
        ,datediff('month', start_date, end_date) as m
    FROM data_table
)
SELECT
    date_trunc('month', dateadd('month', r.rn, d.start_date)) as month
    ,d.start_date
    ,d.end_date
    ,datediff('day', greatest(d.start_date, month), least(d.end_date, dateadd('day', -1, dateadd('month', 1, month))))+1 as days_count
FROM pre_condition as d
JOIN large_range as r ON r.rn <= d.m
ORDER BY d.start_date, month;

给出：

MONTH	START_DATE	END_DATE	DAYS_COUNT
2018-08-01	2018-08-31	2018-10-05	1
2018-09-01	2018-08-31	2018-10-05	30
2018-10-01	2018-08-31	2018-10-05	5
2022-01-01	2022-01-25	2022-02-04	7
2022-02-01	2022-01-25	2022-02-04	4

如果您不喜欢 CTE 的外观

SELECT
    date_trunc('month', dateadd('month', r.rn, d.start_date)) as month
    ,d.start_date
    ,d.end_date
    ,datediff('day', greatest(d.start_date, month), least(d.end_date, dateadd('day', -1, dateadd('month', 1, month))))+1 as days_count
FROM (
    SELECT 
        start_date
        ,end_date
        ,datediff('month', start_date, end_date) as m
    FROM data_table
) as d
JOIN (
    SELECT row_number() over (order by null)-1 as rn
    FROM table(generator(ROWCOUNT => 1000))
) as r ON r.rn <= d.m
ORDER BY d.start_date, month;

雪花 - 给定开始日期和结束日期列，分解每个月并将该月的天数计算到单独的行中

Snowflake - given a start and end date column, break out each month and count number of days for the month into separate rows

sql

snowflake-cloud-data-platform