Add challenge 7

src/data/courses/sql/chapters/sql-basics/lessons/challenge-7.md

@@ -0,0 +1,56 @@
+---
+title: Challenge 7
+description: Write a SQL query to find the total number of orders in the `orders` table.
+order: 700
+type: challenge
+initSteps:
+  - CREATE TABLE orders (
+    id INTEGER PRIMARY KEY,
+    customer_name TEXT NOT NULL,
+    total_amount REAL NOT NULL,
+    shipped_at DATE
+    );
+  - INSERT INTO orders (id, customer_name, total_amount, shipped_at) VALUES
+    (1, 'Alice', 100, '2024-01-01'),
+    (2, 'Bob', 200, NULL),
+    (3, 'Charlie', 300, '2024-01-03'),
+    (4, 'David', 400, NULL),
+    (5, 'Eve', 500, '2024-01-05'),
+    (6, 'Frank', 600, NULL),
+    (7, 'Grace', 700, '2024-01-07'),
+    (8, 'Henry', 800, NULL),
+    (9, 'Henry', 900, '2024-01-09'),
+    (10, 'Ivy', 1000, NULL);
+
+expectedResults:
+  - columns: [id, customer_name, total_amount, shipped_at]
+    values:
+      - [10, 'Ivy', 1000, NULL]
+      - [8, 'Henry', 800, NULL]
+      - [6, 'Frank', 600, NULL]
+---
+
+Given the following table for `orders`:
+
+| id  | customer_name | total_amount | shipped_at |
+| --- | ------------- | ------------ | ---------- |
+| 1   | Alice         | 100          | 2024-01-01 |
+| 2   | Bob           | 200          | NULL       |
+| 3   | Charlie       | 300          | 2024-01-03 |
+| 4   | David         | 400          | NULL       |
+| 5   | Eve           | 500          | 2024-01-05 |
+| 6   | Frank         | 600          | NULL       |
+| 7   | Grace         | 700          | 2024-01-07 |
+| 8   | Henry         | 800          | NULL       |
+| 9   | Henry         | 900          | 2024-01-09 |
+| 10  | Ivy           | 1000         | NULL       |
+
+Write an SQL query to return the top 3 most expensive orders that don't have a `shipped_at` date.
+
+## Expected Results
+
+| id  | customer_name | total_amount | shipped_at |
+| --- | ------------- | ------------ | ---------- |
+| 10  | Ivy           | 1000         | NULL       |
+| 8   | Henry         | 800          | NULL       |
+| 6   | Frank         | 600          | NULL       |

src/data/courses/sql/chapters/sql-basics/lessons/handling-null-values.md

@@ -88,22 +88,3 @@ This query will return the name of the customer and their phone number. If the p
 | Charlie | 555-555-5555 | charlie@example.com |
 | Eve     | 555-777-8888 | eve@example.com     |
 | Grace   | 555-444-3333 | grace@example.com   |
-
----
-
-## Challenge
-
-Given the following table for `orders` write a query to return the top 3 most expensive orders that don't have a `shipped_at` date.
-
-| id  | customer_id | total_amount | shipped_at |
-| --- | ----------- | ------------ | ---------- |
-| 1   | 1           | 100          | 2024-01-01 |
-| 2   | 2           | 200          | NULL       |
-| 3   | 3           | 300          | 2024-01-03 |
-| 4   | 4           | 400          | NULL       |
-| 5   | 5           | 500          | 2024-01-05 |
-| 6   | 6           | 600          | NULL       |
-| 7   | 7           | 700          | 2024-01-07 |
-| 8   | 8           | 800          | NULL       |
-| 9   | 9           | 900          | 2024-01-09 |
-| 10  | 10          | 1000         | NULL       |