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LeetCode SQL 50 Solution/1484. Group Sold Products By The Date/readme.md

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+Here’s a well-structured `README.md` for **LeetCode 1484 - Group Sold Products By The Date**, formatted for a GitHub repository:  
+
+```md
+# 🛍️ Group Sold Products By The Date - LeetCode 1484
+
+## 📌 Problem Statement
+You are given a table **Activities** that contains records of products sold on different dates.
+
+Your task is to return:
+- The **number of distinct products** sold on each date.
+- A **comma-separated string** of the product names, sorted **lexicographically**.
+
+The result should be **ordered by `sell_date`**.
+
+---
+
+## 📊 Table Structure
+
+### **Activities Table**
+| Column Name | Type    |
+| ----------- | ------- |
+| sell_date   | date    |
+| product     | varchar |
+
+- This table **does not** have a **primary key**.
+- It may **contain duplicate entries**.
+
+---
+
+## 📊 Example 1:
+### **Input:**
+#### **Activities Table**
+| sell_date  | product    |
+| ---------- | ---------- |
+| 2020-05-30 | Headphone  |
+| 2020-06-01 | Pencil     |
+| 2020-06-02 | Mask       |
+| 2020-05-30 | Basketball |
+| 2020-06-01 | Bible      |
+| 2020-06-02 | Mask       |
+| 2020-05-30 | T-Shirt    |
+
+### **Output:**
+| sell_date  | num_sold | products                     |
+| ---------- | -------- | ---------------------------- |
+| 2020-05-30 | 3        | Basketball,Headphone,T-Shirt |
+| 2020-06-01 | 2        | Bible,Pencil                 |
+| 2020-06-02 | 1        | Mask                         |
+
+### **Explanation:**
+- `2020-05-30`: Sold items → _(Headphone, Basketball, T-Shirt)_  
+  - Sorted → **"Basketball, Headphone, T-Shirt"**  
+- `2020-06-01`: Sold items → _(Pencil, Bible)_  
+  - Sorted → **"Bible, Pencil"**  
+- `2020-06-02`: Sold item → _(Mask)_  
+  - **"Mask"** (only one item)
+
+---
+
+## 🖥 SQL Solution
+
+### ✅ **Using `GROUP_CONCAT` with `DISTINCT`**
+#### **Explanation:**
+- Use `COUNT(DISTINCT product)` to get the **number of distinct products**.
+- Use `GROUP_CONCAT(DISTINCT product ORDER BY product ASC)` to **join product names in alphabetical order**.
+- Group by `sell_date`, then order the result by `sell_date`.
+
+```sql
+SELECT 
+    sell_date, 
+    COUNT(DISTINCT product) AS num_sold,
+    GROUP_CONCAT(DISTINCT product ORDER BY product ASC SEPARATOR ',') AS products
+FROM Activities
+GROUP BY sell_date
+ORDER BY sell_date ASC;
+```
+
+---
+
+## 🐍 Pandas Solution (Python)
+#### **Explanation:**
+- **Group by `sell_date`**.
+- Use `.nunique()` to count distinct products.
+- Use `', '.join(sorted(set(products)))` to sort and concatenate product names.
+
+```python
+import pandas as pd
+
+def group_sold_products(activities: pd.DataFrame) -> pd.DataFrame:
+    grouped_df = (
+        activities.groupby("sell_date")["product"]
+        .agg(lambda x: ", ".join(sorted(set(x))))
+        .reset_index()
+    )
+    grouped_df["num_sold"] = grouped_df["product"].apply(lambda x: len(x.split(",")))
+    return grouped_df.rename(columns={"product": "products"})
+```
+
+---
+
+## 📁 File Structure
+```
+📂 Group-Sold-Products
+│── 📜 README.md
+│── 📜 solution.sql
+│── 📜 solution_pandas.py
+│── 📜 test_cases.sql
+```
+
+---
+
+## 🔗 Useful Links
+- 📖 [LeetCode Problem](https://leetcode.com/problems/group-sold-products-by-the-date/)
+- 📚 [SQL `GROUP BY`](https://www.w3schools.com/sql/sql_groupby.asp)
+- 🐍 [Pandas `groupby()` Documentation](https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.groupby.html)
+```
+
+### Features of this `README.md`:
+✅ **Clear problem statement with tables**  
+✅ **Example with step-by-step explanation**  
+✅ **SQL and Pandas solutions with detailed breakdowns**  
+✅ **File structure for easy organization**  
+✅ **Helpful references for further learning**  
+
+Would you like any modifications? 🚀