我有两个表代表客户产品及其竞争对手产品的数据库:
tmp_match
- from_product_id 和 to_product_id 分别表示客户产品和竞争对手产品之间的匹配。
tmp_price_history
- 显示每个日期每个产品的价格。
我正在尝试编写一个查询,该查询将列出表 tmp_price_history
中的所有日期。对于每个日期,我都想根据表 tmp_match
中的产品匹配对查看客户产品价格与竞争对手产品价格,无论是否有客户产品或竞争对手产品或两者的价格历史记录 :
如果两个价格在特定日期都可用 - 将它们都列在各自的列中
如果只有客户产品的记录 - 仅显示客户价格(并将竞争对手列留空)。
如果只有竞争对手产品的记录 - 在其列中显示竞争对手的价格。
预期结果:
date from_product_id to_product_id cust_price comp_price
1 1 11 99 95
2 1 11 98 94
1 1 12 92
2 1 12 91
2 2 108
我尝试使用这个查询来实现:
select cust_hist.date, from_product_id, to_product_id, cust_hist.price as cust_price,comp_hist.price as comp_price
from tmp_match as matches
left join tmp_price_history cust_hist
on cust_hist.product_id = matches.from_product_id
left join tmp_price_history comp_hist
on comp_hist.product_id = matches.to_product_id
;
但它并没有实现我的目标,如 sql snippet 所示.
最佳答案
我认为您正在寻找这个:
select distinct *
from (SELECT date,
if(group_concat(distinct cust_price), from_product_id, null)as from_product_id,
if(group_concat(distinct comp_price), to_product_id, null) as to_product_id,
group_concat(distinct cust_price) as cust_price,
group_concat(distinct comp_price) as comp_price
FROM (select cust_hist.date,matches.from_product_id,
matches.to_product_id,cust_hist.price cust_price,
comp_hist.price comp_price
from tmp_match matches
inner join tmp_price_history cust_hist on matches.from_product_id = cust_hist.product_id
inner join tmp_price_history comp_hist on matches.to_product_id = comp_hist.product_id
WHERE comp_hist.date = cust_hist.date
union
select comp_hist.date,matches.from_product_id,
matches.to_product_id,null as cust_price,
comp_hist.price comp_price
from tmp_price_history comp_hist
join tmp_match matches
on matches.to_product_id = comp_hist.product_id # and matches.from_product_id is null
union
select cust_hist.date,matches.from_product_id,
matches.to_product_id,
cust_hist.price cust_price,
null comp_price
from tmp_price_history cust_hist
join tmp_match matches
on matches.from_product_id = cust_hist.product_id # and matches.to_product_id is null
order by DATE, from_product_id, to_product_id, cust_price, comp_price) as u
group by date,from_product_id,to_product_id) g
你关于 sql 片段的想法很棒!
关于mysql - 加入两个表而不丢失相关值,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/51350823/