Question

我想按进一步对应于price_type列的结果集进行分组，如果同时存在具有price_type变体和parent_product的产品的数据，则该数据必须仅显示变体

例如，此数据

Product Name  PPID   QTY   PRID  PRICE   PRICE_TYPE 
Shorts         1     10     21    200    variant
Shorts         1     10     21    100    parent_product
Night Suit     1     10     22    200    variant
Night Suit     1     10     22    100    parent_product
Denim          1     10     23    400    parent_product

应该像

Product Name  PPID   QTY   PRID  PRICE   PRICE_TYPE 
Shorts         1     10     21    200    variant
Night Suit     1     10     22    200    variant
Denim          1     10     23    400    parent_product

Answer 1

似乎您想使用{em>有条件排序的row_number()：

select *
from (select *, row_number() over (partition by ProductName 
                                     order by (case when Price_type = 'variant' 
                                                    then 0 else 1
                                               end)
                                  ) as seq
       from table
     ) t
where seq = 1;

Answer 2

下面是获取所需结果的简单查询。

select
  distinct on(product_name),
  t.*
from tab t
order by price_type='variant' desc

Answer 3

您可以使用窗口功能：

SELECT * FROM 
  (
   SELECT * , 
       RANK() OVER (PARTITION BY product_name ORDER BY priority ) AS rank 
   FROM (
          SELECT *, 
               CASE 
                 WHEN price_type='variant' THEN 1 
                 ELSE 2 
               END AS priority 
          FROM yourtable
        ) AS X
  ) AS Y 
WHERE rank=1

合并或分组与特定列postgresql对应的行

3 个答案: