各大平台店鋪的三項評分（物流、服務、商品）變化情況；
商品每日**的變化記錄；
**的實時漲跌浮；
表：主鍵id，商品編號，記錄時的時間，記錄時的**，建立時間。
問題：獲取每個商品每次的變化情況（漲跌幅、漲跌率）。
1、要想高效率的更新漲跌，就肯定不能是逐條資料更新，要通過自連表建立起對應關係，將每一條資料關聯到上一次的**資料。
2、由於資料庫非常龐大，所以可能存在很多垃圾資料，就比如說相關的字段值為null或者非有效值的，這些資料要先排除掉。
select id,goods_code,goods_date,goods_price from test_goods_price_change where goods_price is not null and goods_date is not null;
3、然後在獲取每條資料的上一條資料，同樣也要先排除掉垃圾資料。
select tmp_a.*, max(tmp_b.goods_date) as last_date from
( select id,goods_code,goods_date,goods_price from test_goods_price_change where goods_price is not null and goods_date is not null ) as tmp_a
left join
( select id,goods_code,goods_date,goods_price from test_goods_price_change where goods_price is not null and goods_date is not null ) as tmp_b
on tmp_a.goods_code = tmp_b.goods_code and tmp_a.goods_date > tmp_b.goods_date group by tmp_a.id;
4、獲取到上一條資料後，獲取上條資料對應的商品**。
select tmp_ab.*,tmp_c.goods_price as last_price from
( select tmp_a.*, max(tmp_b.goods_date) as last_date from
( select id,goods_code,goods_date,goodsbxvuucbb_price from test_goods_price_change where goods_price is not null and goods_date is not null ) as tmp_a
left join
( select id,goods_code,goods_date,goods_price from test_goods_price_change where goods_price is not null and goods_date is not null ) as tmp_b
on tmp_a.goods_code = tmp_b.goods_code and tmp_a.goods_date > tmp_b.goods_date group by tmp_a.id
) as tmp_ab
left join (select id,goods_code,goods_date,goods_price from test_goods_price_change where goods_price is not null and goods_date is not null ) as tmp_c
on tmp_ab.www.cppcns.comgoods_code = tmp_c.goods_code and tmp_c.goods_date = tmp_ab.last_date order by tmp_ab.id;
5、獲取到上條資料以及對應的**後，開始進行計算，獲取到最終的結果。
select
*, (convert(goods_price, decimal(10,2)) - convert(last_price, decimal(10,2))) as '漲跌幅',
round((convert(goods_price, decimal(10,2)) - convert(last_price, decimal(10,2)))/convert(last_price, decimal(10,2)), 2) as '漲跌率'
from (
select tmp_ab.*,tmp_c.goods_price as last_price from
( select tmp_a.*, max(tmp_b.goods_date) as last_date from
( select id,goods_code,goods_date,goods_price from test_goods_price_change where goods_price is not null and goods_date is not null ) as tmp_a
left join
( select id,goods_code,goods_date,goods_price from test_goods_price_change where goods_price is not null and goods_date is not null ) as tmp_b
on tmp_a.goods_code = tmp_b.goods_code and tmp_a.goods_date > tmp_b.goods_date group by tmp_a.id
) as tmp_ab
left join (select id,goods_code,goods_date,goods_price from test_goods_price_change where goods_price is not null and goods_date is not null ) as tmp_c
on tmp_ab.goods_code = tmp_c.goods_code and tmp_c.goods_date = tmp_ab.last_date order by tmp_ab.id
) as tmp
-- 建立表sql
create table `test_goods_price_change` (
`id` int(11) not null auto_increment comment '主鍵id',
`goods_code` varchar(50) not null comment '商品編碼',
`goods_date` int(11) not null comment '記錄時的時間',
`goods_price` decimal(10,2) not null comment '記錄時的**',
`created_at` int(11) not null comment '建立時間',
primary key (`id`)
) engine=innodb charset=utf8mb4;
-- 獲取漲跌浮sql
select
*, (convert(goods_price, debxvuucbbcimal(10,2)) - convert(last_price, decimal(10,2))) as '漲跌幅',
round((convert(goods_price, decimal(10,2)) - convert(last_price, decimal(10,2)))/convert(last_price, decimal(10,2bxvuucbb)), 2) as '漲跌率'
from (
select tmp_ab.*,tmp_c.goods_price as last_price from
( select tmp_a.*, max(tmp_b.goods_date) as last_date from
( select id,goods_code,goods_date,goods_price from test_goods_price_change where goods_price is not null and goods_date is not null ) as tmp_a
left join
( select id,goods_code,goods_date,goods_price from test_goods_price_change where goods_price is not null and goods_date is not null ) as tmp_b
on tmp_a.goods_code = tmp_b.goods_code and tmp_a.goods_date > tmp_b.goods_date group by tmp_a.id
) as tmp_ab
left join (select id,goods_code,goods_date,goods_price from test_goods_price_change where goods_price is not null and goods_date is not null ) as tmp_c
on tmp_ab.goods_code = tmp_c.goods_www.cppcns.comcode and tmp_c.goods_date = tmp_ab.last_date order by tmp_ab.id
) as tmp
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