Postgres：获取多对多关系表中的最小和最大行数

通过窗口函数将供应商的数量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_countFROM  (   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)   ) subGROUP  BY 1ORDER  BY 1;

SQL。