Add modifying tables query

src/data/courses/sql/chapters/data-definition-language/lessons/modifying-table.md

@@ -0,0 +1,65 @@
+---
+title: Modifying Tables
+description: Practice modifying table structure using ALTER TABLE statements
+order: 350
+type: challenge
+setup: |
+  ```sql
+  CREATE TABLE products (
+      id INTEGER,
+      product_name VARCHAR(100),
+      description TEXT,
+      price DECIMAL(10,2),
+      stock_quantity INTEGER,
+      last_updated TIMESTAMP,
+
+      CONSTRAINT pk_products PRIMARY KEY (id),
+      CONSTRAINT chk_price CHECK (price > 0),
+      CONSTRAINT chk_stock CHECK (stock_quantity >= 0)
+  );
+  ```
+---
+
+Given the following `products` table structure:
+
+| Column         | Type          | Constraints                 |
+| -------------- | ------------- | --------------------------- |
+| id             | INTEGER       | PRIMARY KEY                 |
+| product_name   | VARCHAR(100)  |                             |
+| description    | TEXT          |                             |
+| price          | DECIMAL(10,2) | CHECK (price > 0)           |
+| stock_quantity | INTEGER       | CHECK (stock_quantity >= 0) |
+| last_updated   | TIMESTAMP     |                             |
+
+Write SQL statements to make the following modifications to the table structure:
+
+1. Remove the `description` column as it's no longer needed
+2. Add a new `category` column of type `VARCHAR(50)` that cannot be NULL
+3. Change the data type of `price` to `DECIMAL(12,2)` to allow for higher prices
+4. Remove the constraint named `chk_stock`
+5. Add a new `UNIQUE` constraint on the `product_name` column named `unq_product_name`
+
+## Expected Output
+
+After executing your query, the table should be modified successfully with all specified changes. You can verify the result of your changes under the `Schema` tab.
+
+> Note, click the `Reset` button to reset to initial state if you want to try again.
+
+## Solution
+
+```sql
+-- Remove the description column
+ALTER TABLE products DROP COLUMN description;
+
+-- Add the category column
+ALTER TABLE products ADD COLUMN category VARCHAR(50) NOT NULL DEFAULT 'Uncategorized';
+
+-- Modify the price column type
+ALTER TABLE products ALTER COLUMN price TYPE DECIMAL(12,2);
+
+-- Remove the stock quantity check constraint
+ALTER TABLE products DROP CONSTRAINT chk_stock;
+
+-- Add unique constraint on product_name
+ALTER TABLE products ADD CONSTRAINT unq_product_name UNIQUE (product_name);
+```

src/data/courses/sql/chapters/data-definition-language/lessons/sales-data-analysis.md

@@ -1,5 +1,5 @@
 ---
-title: Data Analysis Challenge
+title: Sales Data Analysis
 description: Practice querying temporal data from a bookstore's sales records
 order: 340
 type: challenge