[英]Combine latest records with table
我正在使用mysql,並且具有以下兩個表:
產品 :
| id | name |
|----|-----------|
| 1 | Product 1 |
| 2 | Product 2 |
| 3 | Product 3 |
價格 :
| id | Product_id | created_at | prices |
|----|------------|---------------------|--------|
| 1 | 1 | 2017-12-23 08:32:11 | 10 |
| 2 | 1 | 2017-11-21 03:33:10 | 12 |
| 3 | 2 | 2017-12-23 08:32:11 | 43 |
| 4 | 2 | 2017-11-21 03:33:10 | 23 |
| 5 | 3 | 2017-12-23 08:32:11 | 78 |
| 6 | 3 | 2017-11-21 03:33:10 | 34 |
如果我做:
SELECT * FROM prices WHERE prices.id IN ( SELECT MAX(prices.id) FROM prices GROUP BY prices.created_at )
這為我提供了每個product_id的最新價格:
| id | Product_id | created_at | prices |
|----|------------|---------------------|--------|
| 1 | 1 | 2017-12-23 08:32:11 | 10 |
| 3 | 2 | 2017-12-23 08:32:11 | 43 |
| 5 | 3 | 2017-12-23 08:32:11 | 78 |
我希望最終的結果是所有具有最新價格的產品,如下所示:
| id | name | product_id | created_at | prices |
|----|-----------|------------|---------------------|--------|
| 1 | Product 1 | 1 | 2017-12-23 08:32:11 | 10 |
| 2 | Product 2 | 2 | 2017-12-23 08:32:11 | 43 |
| 3 | Product 3 | 3 | 2017-12-23 08:32:11 | 78 |
但是,我不確定如何結合:
select * from products
和
SELECT * FROM prices WHERE prices.id IN ( SELECT MAX(prices.id) FROM prices GROUP BY prices.created_at )
非常感謝您的回復!
假設您的第一個查詢給您期望的結果,只需使用join
。
SELECT p.*,d.name FROM prices p
inner join product d
on d.id=p.product_id
WHERE
p.id IN
( SELECT MAX(prices.id) FROM prices GROUP BY prices.created_at )
如果您認為price
中存在未在product
映射的產品ID,請使用left join
代替inner join
。
我認為您已獲得商品名稱的最高總價,因此以下是根據給定表查詢的價格
選擇prices.id,products.id,products.product,sum(prices.prices)作為價格中的Totalprices,將prices.id = products.id上的產品與prices.id分組,按prices.id分組,按Totalprices desc限制1
希望對你有幫助
假設最新價格是最近創建的價格,並由prices.created_at
值描述, prices.created_at
獲得最新價格,您最好依賴prices.created_at
,而不是假設按prices.id
(自動增量)的時間順序排列,例如:
SELECT products.id, products.name, prices.created_at, prices.prices
FROM products
INNER JOIN prices ON products.id=prices.product_id
INNER JOIN
(SELECT product_id, MAX(created_at) AS created_at FROM prices GROUP BY product_id) AS LATEST_PRICES
on prices.product_id=LATEST_PRICES.product_id
-- WHERE prices.created_at = LATEST_PRICES.created_at
AND prices.created_at = LATEST_PRICES.created_at
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