task: #1164

README.md

@@ -88,6 +88,7 @@ Have a good contributing!
     - [1045. Customers Who Bought All Products](./leetcode/medium/1045.%20Customers%20Who%20Bought%20All%20Products.sql)
     - [1070. Product Sales Analysis III](./leetcode/medium/1070.%20Product%20Sales%20Analysis%203.sql)
     - [1158. Market Analysis 1](./leetcode/medium/1158.%20Market%20Analysis%201.sql)
+    - [1164. Product Price at a Given Date](./leetcode/medium/1164.%20Product%20Price%20at%20a%20Given%20Date.sql)
     - [1174. Immediate Food Delivery II](./leetcode/medium/1174.%20Immediate%20Food%20Delivery%20II.sql)
     - [1193. Monthly Transactions I](./leetcode/medium/1193.%20Monthly%20Transactions%20I.sql)
     - [1204. Last Person to Fit in the Bus](./leetcode/medium/1204.%20Last%20Person%20to%20Fit%20in%20the%20Bus.sql)

leetcode/medium/1164. Product Price at a Given Date.sql

@@ -0,0 +1,36 @@
+/*
+Question 1164. Product Price at a Given Date
+Link: https://leetcode.com/problems/product-price-at-a-given-date/description/?envType=study-plan-v2&envId=top-sql-50
+
+Table: Products
+
++---------------+---------+
+| Column Name   | Type    |
++---------------+---------+
+| product_id    | int     |
+| new_price     | int     |
+| change_date   | date    |
++---------------+---------+
+(product_id, change_date) is the primary key (combination of columns with unique values) of this table.
+Each row of this table indicates that the price of some product was changed to a new price at some date.
+Initially, all products have price 10.
+
+Write a solution to find the prices of all products on the date 2019-08-16.
+
+Return the result table in any order.
+*/
+
+SELECT DISTINCT
+    p.product_id,
+    COALESCE(
+        (
+            SELECT p1.new_price
+            FROM Products AS p1
+            WHERE
+                p1.change_date <= '2019-08-16' 
+                AND p1.product_id = p.product_id
+            ORDER BY p1.change_date DESC
+            LIMIT 1
+        ), 10
+    ) AS price
+FROM Products AS p