月末休息时间

Question

SQL 服务器 2017

CREATE TABLE [TABLE_1] 
(
    PLAN_NR decimal(28,6) NULL,
    START_DATE datetime NULL,
);

INSERT INTO TABLE_1 (PLAN_NR, START_DATE) 
VALUES (1,'2020-05-01'), (2,'2020-08-01');

CREATE TABLE [TABLE_2] 
(
    PLAN_NR decimal(28,6) NULL,
    PERIOD_NR decimal(28,6) NOT NULL
);
   
INSERT INTO TABLE_2 (PLAN_NR, PERIOD_NR) 
VALUES (1, 1), (1, 2), (1, 3), (1, 4), (1, 5), (1, 6), (1, 7), (1, 8),
       (2, 1), (2, 2), (2, 3), (2, 4), (2, 5), (2, 6), (2, 7), (2, 8);

SQL-FIDDLE-LINK

在TABLE_1中有计划编号和计划开始日期。

TABLE_2 包含每个计划编号的期间编号。

我想计算相应的期间开始日期：

每个周期正好是 7 天，除非周期包含月末。那么期间应该分为月末前到月末（包括月末）和月末后的区间。

Select:

SELECT 
    t1.PLAN_NR, t2.PERIOD_NR, 
    FORMAT(DATEADD (d ,((t2.PERIOD_NR-1)*7) , t1.START_DATE ),'yyyy-MM-dd') START_DATE
FROM
    TABLE_1 t1
JOIN
    TABLE_2 t2 ON t1.PLAN_NR = t2.PLAN_NR
ORDER BY 
    t1.PLAN_NR, t2.PERIOD_NR ASC

此 returns 开始数据但没有额外考虑相应月末：

+---------+-----------+------------+
| PLAN_NR | PERIOD_NR | START_DATE |
+---------+-----------+------------+
|       1 |         1 | 2020-05-01 |
|       1 |         2 | 2020-05-08 |
|       1 |         3 | 2020-05-15 |
|       1 |         4 | 2020-05-22 |
|       1 |         5 | 2020-05-29 |
|       1 |         6 | 2020-06-05 |
|       1 |         7 | 2020-06-12 |
|       1 |         8 | 2020-06-19 |
|       2 |         1 | 2020-08-05 |
|       2 |         2 | 2020-08-12 |
|       2 |         3 | 2020-08-19 |
|       2 |         4 | 2020-08-26 |
|       2 |         5 | 2020-09-01 |
|       2 |         6 | 2020-09-02 |
|       2 |         7 | 2020-09-09 |
|       2 |         8 | 2020-09-16 |
+---------+-----------+------------+

我想要这样的输出：

+---------+-----------+----------------------+
| PLAN_NR | PERIOD_NR |      START_DATE      |
+---------+-----------+----------------------+
|       1 |         1 | 2020-05-01           |
|       1 |         2 | 2020-05-08           |
|       1 |         3 | 2020-05-15           |
|       1 |         4 | 2020-05-22           |
|       1 |         5 | 2020-05-29           |< --- period part before new month
|       1 |         6 | 2020-06-01           |< --- period part after new month
|       1 |         7 | 2020-06-05           |
|       1 |         8 | 2020-06-12           |
|       2 |         1 | 2020-08-05           |
|       2 |         2 | 2020-08-12           |
|       2 |         3 | 2020-08-19           |
|       2 |         4 | 2020-08-26           |< --- period part before new month
|       2 |         5 | 2020-09-01           |< --- period part after new month
|       2 |         6 | 2020-09-02           |
|       2 |         7 | 2020-09-09           |
|       2 |         8 | 2020-09-16           |
+---------+-----------+----------------------+

Answer 1

使用window函数（LEAD/LAG）获取周期的开始和结束...

    SELECT t1.PLAN_NR
    , t2.PERIOD_NR
    , FORMAT(DATEADD (d ,((t2.PERIOD_NR-1)*7) , t1.START_DATE ),'yyyy-MM-dd') START_DATE
    , CASE
       WHEN 
        lead(
          FORMAT(DATEADD (d ,((t2.PERIOD_NR-1)*7) , t1.START_DATE ),'yyyy-MM-dd')
          ) over (partition by 
                    FORMAT(DATEADD (d ,((t2.PERIOD_NR-1)*7) , t1.START_DATE ),'yyyy-MM')
                  order by t2.period_nr)
         IS NULL THEN '< --- period part before new month'
       WHEN lag(
          FORMAT(DATEADD (d ,((t2.PERIOD_NR-1)*7) , t1.START_DATE ),'yyyy-MM-dd')
          ) over (partition by 
                    FORMAT(DATEADD (d ,((t2.PERIOD_NR-1)*7) , t1.START_DATE ),'yyyy-MM')
                  order by t2.period_nr)
         IS NULL THEN '< --- period part after new month'
       END as period_break
    from TABLE_1 t1
    join TABLE_2 t2
    on t1.PLAN_NR = t2.PLAN_NR
    order by t1.PLAN_NR, t2.PERIOD_NR asc

SQL Fiddle

PLAN_NR PERIOD_NR   START_DATE  period_break
1       1           2020-05-01  < --- period part after new month
1       2           2020-05-08  (null)
1       3           2020-05-15  (null)
1       4           2020-05-22  (null)
1       5           2020-05-29  < --- period part before new month
1       6           2020-06-05  < --- period part after new month
1       7           2020-06-12  (null)
1       8           2020-06-19  < --- period part before new month
2       1           2020-08-01  < --- period part after new month
2       2           2020-08-08  (null)
2       3           2020-08-15  (null)
2       4           2020-08-22  (null)
2       5           2020-08-29  < --- period part before new month
2       6           2020-09-05  < --- period part after new month
2       7           2020-09-12  (null)
2       8           2020-09-19  < --- period part before new month

Answer 2

SELECT 
    t1.PLAN_NR, t2.PERIOD_NR, 
    --row_number() over() but what if PERIOD_NR is not consecutive?
    t2.PERIOD_NR + SUM(num.n) OVER(PARTITION BY t2.PLAN_NR ORDER BY t2.PERIOD_NR, num.n) AS PERIOD_NR_x,
    FORMAT(CASE WHEN num.n = 1 THEN DATEADD(day, 1, EOMONTH(DATEADD (d ,((t2.PERIOD_NR-1)*7) , t1.START_DATE ))) ELSE DATEADD(d ,((t2.PERIOD_NR-1)*7) , t1.START_DATE ) END, 'yyyy-MM-dd') START_DATE
FROM
    TABLE_1 t1
JOIN
    TABLE_2 t2 ON t1.PLAN_NR = t2.PLAN_NR
CROSS APPLY
(
    SELECT 0 AS n
    UNION ALL
    --new row for month change
    SELECT 1 AS n
    WHERE DATEDIFF(month, DATEADD(d ,(t2.PERIOD_NR-1)*7 , t1.START_DATE), DATEADD(d ,t2.PERIOD_NR*7 , t1.START_DATE)) = 1
) as num    
ORDER BY 
    t1.PLAN_NR, t2.PERIOD_NR ASC

月末休息时间

Break periods at the end of the month

sql

tsql

sql-server

datetime

sql-server-2017