Question

我是SQL的新手，想从列表中创建一个名为“ firstprice”和“ lastprice”的列。首先按零件号划分价格，然后按提取的登记年份（零件价格）订购。我的代码似乎忽略了ORDER BY代码，因为我仅获得该商品的First_Value（价格）。（并且不按年份排序）

SELECT 
Prices."Part",
Prices."Price",
Prices."RegDt"
CAST(FIRST_VALUE("Price" IGNORE NULLS) 
   OVER (PARTITION BY PB."Part" ORDER BY (EXTRACT (YEAR FROM(Prices."RegDt"))))AS INTEGER) AS "FirstPrice",  

CAST(LAST_VALUE("Price" IGNORE NULLS) 
   OVER (PARTITION BY PB."Part" ORDER BY (EXTRACT (YEAR FROM(Prices."RegDt"))))AS INTEGER) AS "FirstPrice",  

FROM Prices

预期的输出是该年的第一笔价格，但我只获得该产品的第一笔价格（每年未显示）

Answer 1

预期产量是当年首次注册价格

因此，您需要在partition子句中添加年份。我还为last_value定义了window子句，否则它是无限制的前一行和当前行，我们希望从此处获取下一行的数据：

select part, price, regdt, 
       first_value(price) over (partition by part, extract (year from(regdt))
                                order by regdt) fp,
       last_value(price) over (partition by part, extract (year from(regdt))
                               order by regdt 
                               range between current row 
                                         and interval '1' year following ) lp
  from prices

^{dbfiddle demo}

依

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