存在负值时仅获取第一行，否则获取最后一个正值

Question

我有隔壁桌

产品	植物	商店	文字	周	日期	库存
123456	A123	Z12	你好世界	1	2001-01-01	20
123456	A123	Z12	你好世界	2	2001-01-08	-15
123456	A123	Z12	你好世界	3	2001-01-16	-20
789123	B345	123	你好世界1	1	2001-01-01	10
789123	B345	123	你好世界1	2	2001-01-08	20
789123	B345	123	你好世界1	3	2001-01-16	30

所以我想获取第一个负值的行，但如果不是负值，则获取最后一个正值。还像这样重组了表格。

产品	植物	商店	文字	开始日期	库存开始	日期_完成	库存_已完成
123456	A123	Z12	你好世界	2001-01-01	20	2001-01-08	-15
789123	B345	123	你好世界1	2001-01-01	10	2001-01-16	30

我尝试了多个查询，但结果最接近的一个如下：

SELECT Product,Plant,Store,Text,Date, Stock FROM table
WHERE (Stock)<0 
order by Product,Plant,Store,Text,Date, Stock asc

我也尝试使用

FETCH FIRST 1 ROWS ONLY

，但我收到了下一个错误

ERROR: Syntax error at or near "FIRST"

。 另一个查询如下：

WITH added_row_number AS (
  SELECT
    *,
    ROW_NUMBER() OVER(PARTITION BY Product,Plant,Store ORDER BY Date ASC) AS row_number
  FROM MM_STOCK
)
SELECT
  *
FROM added_row_number
WHERE (Stock)<0 AND row_number = 1;

但是要注意数据，如果我添加案例陈述，我会收到错误

ERROR: Syntax error at or near "CASE"

。有什么帮助吗？

Answer 1

可以使用一些子选择来解决这个问题

SELECT "Product", "Plant", "Store"
  , (SELECT "Date" FROM Table2 t2 WHERE t1."Product" = t2."Product" AND  t1."Plant" = t2."Plant"
  AND t1."Store"  = t2."Store" ORDER BY "Week" ASC  LIMIT 1) start_date
  
  , (SELECT "Stock" FROM Table2 t2 WHERE t1."Product" = t2."Product" AND  t1."Plant" = t2."Plant"
  AND t1."Store"  = t2."Store"  ORDER BY "Week" ASC LIMIT 1) start_stock
    , (SELECT "Date" FROM Table2 t2 WHERE t1."Product" = t2."Product" AND  t1."Plant" = t2."Plant"
  AND t1."Store" = t2."Store" ORDER BY "Week" DESC LIMIT 1) en_date
  
  , (SELECT "Stock" FROM Table2 t2 WHERE t1."Product" = t2."Product" AND  t1."Plant" = t2."Plant"
  AND t1."Store" = t2."Store"  ORDER BY "Week" DESC LIMIT 1) end_stock
  FROM
 Table2 t1
  GROUP BY 
    "Product", "Plant", "Store"

产品	植物	商店	开始日期	起始库存	en_日期	最终库存
789123	B345	123	2001-01-01	10	2001-01-16	30
123456	A123	Z12	2001-01-01	20	2001-01-16	-20

SELECT 2

小提琴

你不需要这个聚合，我找不到不起作用的版本 postgres

SELECT DISTINCT "Product", "Plant", "Store"
  , (SELECT "Date" FROM Table2 t2 WHERE t1."Product" = t2."Product" AND  t1."Plant" = t2."Plant"
  AND t1."Store"  = t2."Store" ORDER BY "Week" ASC  LIMIT 1) start_date
  
  , (SELECT "Stock" FROM Table2 t2 WHERE t1."Product" = t2."Product" AND  t1."Plant" = t2."Plant"
  AND t1."Store"  = t2."Store"  ORDER BY "Week" ASC LIMIT 1) start_stock
    , (SELECT "Date" FROM Table2 t2 WHERE t1."Product" = t2."Product" AND  t1."Plant" = t2."Plant"
  AND t1."Store" = t2."Store" ORDER BY "Week" DESC LIMIT 1) en_date
  
  , (SELECT "Stock" FROM Table2 t2 WHERE t1."Product" = t2."Product" AND  t1."Plant" = t2."Plant"
  AND t1."Store" = t2."Store"  ORDER BY "Week" DESC LIMIT 1) end_stock
  FROM
 Table2 t1

产品	植物	商店	开始日期	起始库存	en_日期	最终库存
123456	A123	Z12	2001-01-01	20	2001-01-16	-20
789123	B345	123	2001-01-01	10	2001-01-16	30

SELECT 2

小提琴