Sql Postgres：获取多对多关系表中的最小和最大行数

我有RFQ（报价请求）和供应商投标金额的对应表

询价供应商映射：

id  rfq_id(FK)  vendor_id(FK)   amount
---------------------------------------

 1      1           1            100
 2      1           2            50
 3      2           1            200
 4      2           3            300
 5      2           2            40
 6      3           4            70
 7      3           1            90
 8      3           2            250
 9      4           3            30
 10     5           1            500

vendor_id   min_bid_count   max_bid_count
-----------------------------------------
    1           1               2
    2           2               1
    3           1               2
    4           1               0

在上表中，我想分析供应商提交每个RFQ的最低和最高投标次数

预期输出：

id  rfq_id(FK)  vendor_id(FK)   amount
---------------------------------------

 1      1           1            100
 2      1           2            50
 3      2           1            200
 4      2           3            300
 5      2           2            40
 6      3           4            70
 7      3           1            90
 8      3           2            250
 9      4           3            30
 10     5           1            500

vendor_id   min_bid_count   max_bid_count
-----------------------------------------
    1           1               2
    2           2               1
    3           1               2
    4           1               0

---

通过窗口函数将供应商的金额与最小值和最大值进行比较，并在外部查询级别上运行条件计数：

SELECT vendor_id
     , count(min_bid OR NULL) AS min_bid_count
     , count(max_bid OR NULL) AS max_bid_count
FROM  (
   SELECT vendor_id
        , amount = min(amount) OVER w AS min_bid
        , amount = max(amount) OVER w AS max_bid
   FROM   rfq_vendor_mapping
   WINDOW w AS (PARTITION BY rfq_id)
   ) sub
GROUP  BY 1
ORDER  BY 1;

显然，任何SQL都“在JPA中受支持”，如果您希望使用JPQL，那么您必须提供这些类供任何人评论。这不是查询写入服务。请查看