From bb48ca1f7cb29fcfcaaef0cd835b304c9e58283c Mon Sep 17 00:00:00 2001
From: Kamran Ahmed <kamranahmed.se@gmail.com>
Date: Sun, 29 Dec 2024 18:00:32 +0000
Subject: [PATCH] Add updating data lesson

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+---
+title: Updating Data
+description: Learn how to update data in a table.
+order: 110
+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);
+  ```
+---
+
+An `UPDATE` statement is used to change the values of one or more columns in existing rows. For example, let's say we have the same `books` table from the previous lesson 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  |
+
+### Updating a Single Row
+
+To update a specific book's price, we can use:
+
+```sql
+UPDATE books
+SET price = 11.99
+WHERE id = 1;
+```
+
+This will update only the price of `The Great Gatsby`:
+
+| id  | title                 | author              | price |
+| --- | --------------------- | ------------------- | ----- |
+| 1   | The Great Gatsby      | F. Scott Fitzgerald | 11.99 |
+| 2   | 1984                  | George Orwell       | 12.99 |
+| 3   | To Kill a Mockingbird | Harper Lee          | 8.99  |
+| 4   | Animal Farm           | George Orwell       | 9.99  |
+
+### Updating Multiple Columns
+
+You can update multiple columns in a single statement:
+
+```sql
+UPDATE books
+SET title = 'Nineteen Eighty-Four',
+    price = 13.99
+WHERE id = 2;
+```
+
+### Updating Multiple Rows
+
+You can update all books by a specific author:
+
+```sql
+UPDATE books
+SET price = price + 2.00
+WHERE author = 'George Orwell';
+```
+
+### Using Expressions in Updates
+
+You can use expressions and calculations in your updates:
+
+```sql
+-- Give a $1 discount to all books over $10
+UPDATE books
+SET price = price - 1
+WHERE price > 10;
+
+-- Add "(Classic Edition)" to all titles
+UPDATE books
+SET title = CONCAT(title, ' (Classic Edition)');
+```
+
+> `CONCAT` is a function that concatenates two strings.
+
+### Updating All Rows
+
+You can update all rows by omitting the WHERE clause:
+
+```sql
+UPDATE books
+SET price = price + 1;
+```
+
+> ⚠️ Warning: Be careful when updating all rows! Some database systems require you to explicitly enable this operation to prevent accidents. It's good practice to first run a SELECT query to verify which rows will be affected.
+
+---
+
+## Challenge
+
+I have created a `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  |
+
+Write the following `UPDATE` statements:
+
+1. Increase the price of all books by `1`
+2. Add `(Paperback)` to book titles that cost less than `12`
+3. Update and set the author name to `Fitzgerald` for all the books by `F. Scott Fitzgerald`
+
+> You can run multiple `UPDATE` statements in a single query. Just separate them with a semicolon.