自动计算列名 sql

Question

有没有办法在 SQL 中自动计算列名，如下所示。我需要根据从和到日期计算日历周并均匀分布

Material	From	To	Sales
M01	03.10.2022	31.10.2022	1000
M02	14.11.2022	28.11.2022	1000

预期产出

CW =日历周

Material	Cw40	CW41	Cw42	CW43	CW44	CW45	CW46	CW47
M01	250	250	250	250
M02							500	500

Answer 1

有没有办法在 SQL 中自动计算列名，如下所示。

不，在 SQL（不仅仅是 Oracle SQL）中，您需要固定的、已知数量的列名，因此不可能使用静态 SQL 查询动态生成列。

---

如果要生成数据，则可以：

将数据生成为行（而不是列）并在您用于访问数据库的任何第三方应用程序中旋转结果。您可以使用相关的行生成器生成输出：

SELECT t.material,
       w.iso_year,
       w.iso_week,
       w.weekly_sales
FROM   table_name t
       CROSS APPLY (
         SELECT TO_NUMBER(
                  TO_CHAR(
                    TRUNC(from_dt, 'IW') + INTERVAL '7' DAY * (LEVEL - 1),
                    'IYYY'
                  )
                ) AS iso_year,
                TO_NUMBER(
                  TO_CHAR(
                    TRUNC(from_dt, 'IW') + INTERVAL '7' DAY * (LEVEL - 1),
                    'IW'
                  )
                ) AS iso_week,
                ( LEAST(
                    TRUNC(from_dt, 'IW') + INTERVAL '7' DAY * LEVEL,
                    to_dt
                  )
                  - GREATEST(
                    TRUNC(from_dt, 'IW') + INTERVAL '7' DAY * (LEVEL - 1),
                    from_dt
                  )
                ) / (to_dt - from_dt) * sales AS weekly_sales
         FROM   DUAL
         CONNECT BY TRUNC(from_dt, 'IW') + INTERVAL '7' DAY * (LEVEL-1) < to_dt
       ) w

或者：

WITH data (from_dt, dt, to_dt, material, sales) AS (
  SELECT from_dt, from_dt, to_dt, material, sales
  FROM   table_name
UNION ALL
  SELECT from_dt,
         TRUNC(dt + INTERVAL '7' DAY, 'IW'),
         to_dt,
         material,
         sales
  FROM   data
  WHERE  TRUNC(dt + INTERVAL '7' DAY, 'IW') < to_dt
)
SELECT material,
       TO_NUMBER(TO_CHAR(dt, 'IYYY')) AS iso_year,
       TO_NUMBER(TO_CHAR(dt, 'IW')) AS iso_week,
       ( LEAST(dt + INTERVAL '7' DAY, to_dt) - dt)
         / (to_dt - from_dt) * sales AS weekly_sales
FROM   data

其中，对于样本数据：

CREATE TABLE table_name (Material, From_dt, To_dt, Sales) AS
SELECT 'M01', DATE '2022-10-03', DATE '2022-10-31', 1000 FROM DUAL UNION ALL
SELECT 'M02', DATE '2022-11-14', DATE '2022-11-28', 1000 FROM DUAL;

两个输出：

MATERIAL	ISO_YEAR	ISO_WEEK	WEEKLY_SALES
M01	2022	40	250
M01	2022	41	250
M01	2022	42	250
M01	2022	43	250
M02	2022	46	500
M02	2022	47	500

或者，如果您确实想将值输出为列，那么您需要指定列（对于所有 53 个潜在的 ISO 周，这将是 53 列）并且可以使用以下方法执行此操作：

SELECT *
FROM   (
  SELECT t.material,
         w.iso_year,
         w.iso_week,
         w.weekly_sales
  FROM   table_name t
         CROSS APPLY (
           SELECT TO_NUMBER(
                    TO_CHAR(
                      TRUNC(from_dt, 'IW') + INTERVAL '7' DAY * (LEVEL - 1),
                      'IYYY'
                    )
                  ) AS iso_year,
                  TO_NUMBER(
                    TO_CHAR(
                      TRUNC(from_dt, 'IW') + INTERVAL '7' DAY * (LEVEL - 1),
                      'IW'
                    )
                  ) AS iso_week,
                  ( LEAST(
                      TRUNC(from_dt, 'IW') + INTERVAL '7' DAY * LEVEL,
                      to_dt
                    )
                    - GREATEST(
                      TRUNC(from_dt, 'IW') + INTERVAL '7' DAY * (LEVEL - 1),
                      from_dt
                    )
                  ) / (to_dt - from_dt) * sales AS weekly_sales
           FROM   DUAL
           CONNECT BY TRUNC(from_dt, 'IW') + INTERVAL '7' DAY * (LEVEL-1) < to_dt
         ) w
)
PIVOT (
  SUM(weekly_sales)
  FOR iso_week IN (
     1 AS cw01,
     2 AS cw02,
     3 AS cw03,
    -- ...
    40 AS cw40,
    41 AS cw41,
    42 AS cw42,
    43 AS cw43,
    44 AS cw44,
    45 AS cw45,
    46 AS cw46,
    47 AS cw47,
    48 AS cw48,
    49 AS cw49,
    50 AS cw50,
    51 AS cw51,
    52 AS cw52,
    53 AS cw53
  )
)

或者：

WITH data (from_dt, dt, to_dt, material, sales) AS (
  SELECT from_dt, from_dt, to_dt, material, sales
  FROM   table_name
UNION ALL
  SELECT from_dt,
         TRUNC(dt + INTERVAL '7' DAY, 'IW'),
         to_dt,
         material,
         sales
  FROM   data
  WHERE  TRUNC(dt + INTERVAL '7' DAY, 'IW') < to_dt
)
SELECT *
FROM   (
  SELECT material,
         TO_NUMBER(TO_CHAR(dt, 'IYYY')) AS iso_year,
         TO_NUMBER(TO_CHAR(dt, 'IW')) AS iso_week,
         ( LEAST(dt + INTERVAL '7' DAY, to_dt) - dt)
           / (to_dt - from_dt) * sales AS weekly_sales
  FROM   data
)
PIVOT (
  SUM(weekly_sales)
  FOR iso_week IN (
     1 AS cw01,
     2 AS cw02,
     3 AS cw03,
    -- ...
    40 AS cw40,
    41 AS cw41,
    42 AS cw42,
    43 AS cw43,
    44 AS cw44,
    45 AS cw45,
    46 AS cw46,
    47 AS cw47,
    48 AS cw48,
    49 AS cw49,
    50 AS cw50,
    51 AS cw51,
    52 AS cw52,
    53 AS cw53
  )
)

两者都输出：

MATERIAL	ISO_YEAR	CW01	CW02	CW03	CW40	CW41	CW42	CW43	CW44	CW45	CW46	CW47	CW48	CW49	CW50	CW51	CW52	CW53
M01	2022	null	null	null	250	250	250	250	null	null	null	null	null	null	null	null	null	null
M02	2022	null	null	null	null	null	null	null	null	null	500	500	null	null	null	null	null	null

fiddle