Add delete operations

src/data/courses/sql/chapters/manipulating-data/lessons/delete-operations.md

@@ -0,0 +1,119 @@
+---
+title: DELETE Operations
+description: Learn how to delete data from a table.
+order: 130
+type: lesson-challenge
+setup: |
+  ```sql
+  CREATE TABLE books (
+      id INTEGER PRIMARY KEY,
+      title VARCHAR(100),
+      author VARCHAR(100),
+      price DECIMAL(10,2)
+  );
+
+  INSERT INTO books (id, title, author, price) VALUES
+      (1, 'The Great Gatsby', 'F. Scott Fitzgerald', 10.99),
+      (2, '1984', 'George Orwell', 12.99),
+      (3, 'To Kill a Mockingbird', 'Harper Lee', 8.99),
+      (4, 'Animal Farm', 'George Orwell', 9.99);
+  ```
+---
+
+A `DELETE` statement is used to remove rows from a table. Let's look at different ways to delete data from our `books` table:
+
+| id  | title                 | author              | price |
+| --- | --------------------- | ------------------- | ----- |
+| 1   | The Great Gatsby      | F. Scott Fitzgerald | 10.99 |
+| 2   | 1984                  | George Orwell       | 12.99 |
+| 3   | To Kill a Mockingbird | Harper Lee          | 8.99  |
+| 4   | Animal Farm           | George Orwell       | 9.99  |
+
+### Deleting a Single Row
+
+To delete a specific book, we can use:
+
+```sql
+DELETE FROM books
+WHERE id = 1;
+```
+
+This will remove 'The Great Gatsby' from the table:
+
+| id  | title                 | author        | price |
+| --- | --------------------- | ------------- | ----- |
+| 2   | 1984                  | George Orwell | 12.99 |
+| 3   | To Kill a Mockingbird | Harper Lee    | 8.99  |
+| 4   | Animal Farm           | George Orwell | 9.99  |
+
+### Deleting Multiple Rows
+
+You can delete all books by a specific author:
+
+```sql
+DELETE FROM books
+WHERE author = 'George Orwell';
+```
+
+### Deleting with Complex Conditions
+
+You can use various conditions to target specific rows:
+
+```sql
+-- Delete books that cost more than $10
+DELETE FROM books
+WHERE price > 10;
+
+-- Delete books with specific titles
+DELETE FROM books
+WHERE title IN ('1984', 'Animal Farm');
+
+-- Delete books based on multiple conditions
+DELETE FROM books
+WHERE author = 'George Orwell'
+AND price < 10;
+```
+
+### Deleting All Rows
+
+To delete all rows from a table, you can use:
+
+```sql
+DELETE FROM books;
+```
+
+> ⚠️ Warning: Be very careful with this command! It will remove all data from the table. Some database systems require you to explicitly enable this operation to prevent accidents.
+
+### DELETE vs TRUNCATE
+
+In the previous chapter, we learned about `TRUNCATE` to remove all the rows from a table. You can use `DELETE` to achieve the same result i.e. both of the following will achieve the same result:
+
+```sql
+DELETE FROM books;
+TRUNCATE TABLE books;
+```
+
+However, without going into much detail, `TRUNCATE` is faster than `DELETE` when removing all rows from a table. On the other hand, `DELETE` is more flexible and allows you to roll back the operation if needed (when using transactions, which we will learn about in future chapters).
+
+> 💡 Use `TRUNCATE` when you want to quickly remove all data and reset the table to its initial state. Use `DELETE` when you need transaction control or when removing specific rows.
+
+---
+
+## Challenge
+
+Using the `books` table with the following data:
+
+| id  | title                 | author              | price |
+| --- | --------------------- | ------------------- | ----- |
+| 1   | The Great Gatsby      | F. Scott Fitzgerald | 10.99 |
+| 2   | 1984                  | George Orwell       | 12.99 |
+| 3   | To Kill a Mockingbird | Harper Lee          | 8.99  |
+| 4   | Animal Farm           | George Orwell       | 9.99  |
+
+Write the following `DELETE` statements:
+
+1. Delete all books that cost more than `10`
+2. Delete all books by `George Orwell`
+3. Delete the book with `id = 3`
+
+> Remember to use semicolons to separate multiple `DELETE` statements.

src/data/courses/sql/chapters/manipulating-data/lessons/update-operations.md

@@ -1,5 +1,5 @@
 ---
-title: Updating Data
+title: UPDATE Operations
 description: Learn how to update data in a table.
 order: 110
 type: lesson-challenge