select something, somthingelse,
(
select * from
(
select QUOTE_PRICE as old_price
from price_history
where price_history.part_no= article_table.part_no
order by valid_from desc
) where rownum=1
)
from article_table where rownum < 5
!> 这里是会报：SQL Error: ORA-00904: “article_table “.”part_no”: invalid identifier
-
说明：在oracle中，子查询只能嵌套两层，否则就不能识别到第三层的就不能识别到第一层的table。
-
解决方案： 按
列分片，各自分片中各自计算row_number
-- 外层嵌套为获取每个分片第一条
SELECT something, somthingelse, old_price
FROM (
SELECT a.something, a.somthingelse, p.quote_price old_price,
-- 分片键 + 排序方式
row_number() over (PARTITION BY a.part_no ORDER BY valid_from DESC) rnk
FROM article_table a
LEFT JOIN price_history p ON a.part_no = p.part_no
) WHERE rnk = 1;