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LeetCode SQL 50 Solution/1068. Product Sales Analysis I/readme.md

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+# **1068. Product Sales Analysis I**
+
+## **Problem Statement**
+You are given two tables:  
+
+- `Sales` (contains sales data including `product_id`, `year`, `quantity`, and `price`).  
+- `Product` (contains `product_id` and `product_name`).
+
+Each `product_id` in `Sales` is a **foreign key** referring to the `Product` table.
+
+### **Sales Table**
+```
++---------+------------+------+----------+-------+
+| sale_id | product_id | year | quantity | price |
++---------+------------+------+----------+-------+
+| int     | int        | int  | int      | int   |
++---------+------------+------+----------+-------+
+```
+- `(sale_id, year)` is the **primary key** (unique values).
+- `product_id` refers to the `Product` table.
+- `price` represents the **per unit price** of the product in that year.
+
+### **Product Table**
+```
++------------+--------------+
+| product_id | product_name |
++------------+--------------+
+| int        | varchar      |
++------------+--------------+
+```
+- `product_id` is the **primary key** of this table.
+
+### **Task:**
+Find the `product_name`, `year`, and `price` for each sale in the `Sales` table.
+
+---
+
+## **Example 1:**
+
+### **Input:**
+**Sales Table**
+```
++---------+------------+------+----------+-------+
+| sale_id | product_id | year | quantity | price |
++---------+------------+------+----------+-------+
+| 1       | 100        | 2008 | 10       | 5000  |
+| 2       | 100        | 2009 | 12       | 5000  |
+| 7       | 200        | 2011 | 15       | 9000  |
++---------+------------+------+----------+-------+
+```
+
+**Product Table**
+```
++------------+--------------+
+| product_id | product_name |
++------------+--------------+
+| 100        | Nokia        |
+| 200        | Apple        |
+| 300        | Samsung      |
++------------+--------------+
+```
+
+### **Output:**
+```
++--------------+-------+-------+
+| product_name | year  | price |
++--------------+-------+-------+
+| Nokia        | 2008  | 5000  |
+| Nokia        | 2009  | 5000  |
+| Apple        | 2011  | 9000  |
++--------------+-------+-------+
+```
+
+### **Explanation:**
+- **Sale ID 1:** `Nokia` was sold in **2008** for **5000**.
+- **Sale ID 2:** `Nokia` was sold in **2009** for **5000**.
+- **Sale ID 7:** `Apple` was sold in **2011** for **9000**.
+
+---
+
+## **SQL Solutions**
+
+### **1️⃣ Standard MySQL Solution**
+```sql
+SELECT p.product_name, s.year, s.price
+FROM Sales s
+JOIN Product p ON s.product_id = p.product_id;
+```
+#### **Explanation:**
+1. **JOIN** the `Sales` table with the `Product` table using `product_id`.
+2. **Select `product_name`, `year`, and `price`** from the joined result.
+
+---
+
+### **2️⃣ Window Function (SQL) Solution**
+```sql
+WITH SalesData AS (
+    SELECT s.product_id, s.year, s.price, p.product_name
+    FROM Sales s
+    JOIN Product p ON s.product_id = p.product_id
+)
+SELECT product_name, year, price 
+FROM SalesData;
+```
+#### **Explanation:**
+1. **CTE `SalesData`** → Stores the joined data from `Sales` and `Product`.
+2. **Final SELECT** → Retrieves `product_name`, `year`, and `price`.
+
+---
+
+## **Pandas Solution (Python)**
+```python
+import pandas as pd
+
+# Sample Data
+sales_data = {'sale_id': [1, 2, 7], 
+              'product_id': [100, 100, 200], 
+              'year': [2008, 2009, 2011], 
+              'quantity': [10, 12, 15], 
+              'price': [5000, 5000, 9000]}
+
+product_data = {'product_id': [100, 200, 300], 
+                'product_name': ['Nokia', 'Apple', 'Samsung']}
+
+# Create DataFrames
+sales_df = pd.DataFrame(sales_data)
+product_df = pd.DataFrame(product_data)
+
+# Perform Join
+result = sales_df.merge(product_df, on='product_id')[['product_name', 'year', 'price']]
+
+print(result)
+```
+
+### **Explanation:**
+1. **Create DataFrames** → Convert `Sales` and `Product` tables into Pandas DataFrames.
+2. **Perform `merge()` on `product_id`** → Equivalent to SQL `JOIN`.
+3. **Select required columns (`product_name`, `year`, `price`)**.
+
+---
+
+## **File Structure**
+```
+LeetCode1068/
+├── problem_statement.md       # Contains the problem description and constraints.
+├── sql_solution.sql           # Contains the SQL solutions (Standard + Window Functions).
+├── pandas_solution.py         # Contains the Pandas solution.
+├── README.md                  # Overview of the problem and available solutions.
+```
+
+---
+
+## **Useful Links**
+- [LeetCode Problem 1068](https://leetcode.com/problems/product-sales-analysis-i/)
+- [SQL JOIN Documentation](https://www.w3schools.com/sql/sql_join.asp)
+- [Pandas Merge Documentation](https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.merge.html)
+
+---
+
+This README now includes:
+✅ **MySQL Query**  
+✅ **Window SQL Query**  
+✅ **Pandas Python Solution**  
+✅ **File Structure & Useful Links**  
+
+🚀 **Now it's a complete guide!** 🚀