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`@@ -86,18 +86,25 @@ FROM`
`86`	`86`
`87`	`87`	`### 2️⃣ Window Function (SQL) Solution`
`88`	`88`	```sql
`89`		`-WITH RankedPrices AS (`
`90`		`- SELECT`
`91`		`- product_id,`
`92`		`- new_price AS price,`
`93`		`- change_date,`
`94`		`- RANK() OVER (PARTITION BY product_id ORDER BY change_date DESC) AS rnk`
`95`		`- FROM Products`
`96`		`- WHERE change_date <= '2019年08月16日'`
`97`		`-)`
`98`		`-SELECT p.product_id, COALESCE(rp.price, 10) AS price`
`99`		`-FROM (SELECT DISTINCT product_id FROM Products) p`
`100`		`-LEFT JOIN RankedPrices rp ON p.product_id = rp.product_id AND rp.rnk = 1;`
	`89`	`+# Write your MySQL query statement below`
	`90`	`+# Write your MySQL query statement below`
	`91`	`+WITH`
	`92`	`+ T AS (SELECT DISTINCT product_id FROM Products),`
	`93`	`+ P AS (`
	`94`	`+ SELECT product_id, new_price AS price`
	`95`	`+ FROM Products`
	`96`	`+ WHERE`
	`97`	`+ (product_id, change_date) IN (`
	`98`	`+ SELECT product_id, MAX(change_date) AS change_date`
	`99`	`+ FROM Products`
	`100`	`+ WHERE change_date <= '2019年08月16日'`
	`101`	`+ GROUP BY 1`
	`102`	`+ )`
	`103`	`+ )`
	`104`	`+SELECT product_id, IFNULL(price, 10) AS price`
	`105`	`+FROM`
	`106`	`+ T`
	`107`	`+ LEFT JOIN P USING (product_id);`
`101`	`108`	```
`102`	`109`	`#### Explanation:`
`103`	`110`	1. `RANK() OVER (PARTITION BY product_id ORDER BY change_date DESC)`

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