Merge pull request #442 from michaelmjhhhh/michaelmjhhhh-update-mysql-cheatsheet

Add essential sections to MySQL: Alter, Indexes, and Transactions

README.md

@@ -1,21 +1,29 @@
+<div align="center">
+
 [![AWESOME CHEATSHEETS LOGO](_design/cover_github@2x.png)](https://lecoupa.github.io/awesome-cheatsheets/)
 
-<p align=center>
+<a href="https://trendshift.io/repositories/5584" target="_blank">
-     <a href="https://trendshift.io/repositories/5584" target="_blank"><img src="https://trendshift.io/api/badge/repositories/5584" alt="LeCoupa%2Fawesome-cheatsheets | Trendshift" style="width: 250px; height: 55px;" width="250" height="55"/></a>
+  <img src="https://trendshift.io/api/badge/repositories/5584" alt="LeCoupa%2Fawesome-cheatsheets | Trendshift" width="250" height="55"/>
-</p>
+</a>
 
 [![Awesome](https://awesome.re/badge.svg)](https://awesome.re) [![GitHub license](https://img.shields.io/badge/license-MIT-blue.svg)](https://github.com/LeCoupa/awesome-cheatsheets/blob/master/LICENSE)
 
-**WEBSITE DIRECTORY**: [Available here](https://lecoupa.github.io/awesome-cheatsheets/).
+**WEBSITE DIRECTORY**: [Available here](https://lecoupa.github.io/awesome-cheatsheets/)
 
 > 📚 Awesome cheatsheets for popular programming languages, frameworks and development tools. They include everything you should know in one single file.
 
+</div>
+
+---
+
 ## 🤔 Why Awesome-Cheatsheets?
 
 I usually make a cheat sheet when I want to improve my skills in a programming language, a framework or a development tool. [I started doing these kinds of things a long time ago on Gist](https://gist.github.com/LeCoupa). To better keep track of the history and to let people contribute, I re-organized all of them into this single repository. Most of the content is coming from official documentation and some books I have read.
 
 Feel free to take a look. You might learn new things. They have been designed to provide a quick way to assess your knowledge and to save you time.
 
+---
+
 ## 📚 Table of Contents
 
 ### 📃 Languages
@@ -24,47 +32,47 @@ Feel free to take a look. You might learn new things. They have been designed to
 <summary>View cheatsheets</summary>
 
 #### Command line interface
-
 - [Bash](languages/bash.sh)
 
 #### Imperative
-
 - [C](languages/C.txt)
 - [C#](languages/C%23.txt)
 - [Go](languages/golang.md)
 - [Java](languages/java.md)
 - [PHP](languages/php.php)
 - [Python](languages/python.md)
+- [XML](languages/XML.md)
 
 #### Functional
-
 - [JavaScript](languages/javascript.js)
 - [Typescript](languages/typescript.md)
 
 </details>
 
+---
+
 ### 📦 Backend
 
 <details>
 <summary>View cheatsheets</summary>
 
 #### PHP
-
 - [Laravel](backend/laravel.php)
 
 #### Python
-
 - [Django](backend/django.py)
 
-#### Javascript
+#### JavaScript
-
 - [Adonis.js](backend/adonis.js)
 - [Express.js](backend/express.js)
 - [Feathers.js](backend/feathers.js)
 - [Moleculer](backend/moleculer.js)
 - [Node.js](backend/node.js)
 - [Sails.js](backend/sails.js)
-  </details>
+
+</details>
+
+---
 
 
 ### 🌐 Frontend
@@ -73,23 +81,20 @@ Feel free to take a look. You might learn new things. They have been designed to
 <summary>View cheatsheets</summary>
 
 #### Basics
-
 - [HTML5](frontend/html5.html)
 - [CSS3](frontend/css3.css)
+- [Typescript](frontend/typescript.ts)
 
 #### Frameworks
-
 - [React.js](frontend/react.js)
 - [Vue.js](frontend/vue.js)
 - [Tailwind.css](frontend/tailwind.css)
 - [Ember.js](frontend/ember.js)
 - [Angular (2+)](frontend/angular.js)
 - [AngularJS](frontend/angularjs.js)
+</details>
 
-#### Typescript
+---
-
-- [Typescript](frontend/typescript.ts)
-  </details>
 
 ### 🗃️ Databases
 
@@ -97,13 +102,15 @@ Feel free to take a look. You might learn new things. They have been designed to
 <summary>View cheatsheets</summary>
 
 #### SQL
-
 - [MySQL](databases/mysql.sh)
 
 #### NoSQL
-
+- [MongoDB](databases/mongodb.sh)
 - [Redis](databases/redis.sh)
-  </details>
+
+</details>
+
+---
 
 ### 🔧 Tools
 
@@ -111,7 +118,6 @@ Feel free to take a look. You might learn new things. They have been designed to
 <summary>View cheatsheets</summary>
 
 #### Development
-
 - [cURL](tools/curl.sh)
 - [Drush](tools/drush.sh)
 - [Elasticsearch](tools/elasticsearch.js)
@@ -124,25 +130,35 @@ Feel free to take a look. You might learn new things. They have been designed to
 - [Xcode](tools/xcode.txt)
 
 #### Infrastructure
-
 - [AWS CLI](tools/aws.sh)
 - [Docker](tools/docker.sh)
+- [GCP CLI](tools/gcp.md)
 - [Heroku CLI](tools/heroku.sh)
 - [Kubernetes](tools/kubernetes.md)
+- [macOS](tools/macos.sh)
 - [Nanobox Boxfile](tools/nanobox_boxfile.yml)
 - [Nanobox CLI](tools/nanobox_cli.sh)
 - [Nginx](tools/nginx.sh)
 - [PM2](tools/pm2.sh)
 - [Ubuntu](tools/ubuntu.sh)
 - [Firebase CLI](tools/firebase_cli.md)
-  </details>
+
+</details>
+
+---
 
 ## 🙌🏼 How to Contribute?
 
 You are more than welcome to contribute and build your own cheat sheet for your favorite programming language, framework or development tool. Just submit changes via pull request and I will review them before merging.
 
+---
+
 ## 👩‍💻👨‍💻 Our valuable Contributors
 
-<p align="center"><a href="https://github.com/LeCoupa/awesome-cheatsheets/graphs/contributors">
+<div align="center">
+
+<a href="https://github.com/LeCoupa/awesome-cheatsheets/graphs/contributors">
   <img src="https://contributors-img.web.app/image?repo=LeCoupa/awesome-cheatsheets" />
-</a></p>
+</a>
+
+</div>

databases/mysql.sh

@@ -82,3 +82,33 @@ SELECT User, Host FROM mysql.user; # List all current MySQL users
 
 SET GLOBAL general_log = 'ON'; # Enable query logging
 SHOW FULL PROCESSLIST; # Show the last queries executed in MySQL
+
+# *****************************************************************************
+# Altering Table Structure
+# *****************************************************************************
+
+ALTER TABLE table_name ADD COLUMN column_name datatype;        # Add a new column to an existing table
+ALTER TABLE table_name MODIFY COLUMN column_name datatype;     # Change the data type of a column
+ALTER TABLE table_name RENAME COLUMN old_name TO new_name;     # Rename a column (MySQL 8.0+)
+ALTER TABLE table_name DROP COLUMN column_name;                # Remove a column from a table
+ALTER TABLE old_table_name RENAME TO new_table_name;           # Rename an entire table
+
+# *****************************************************************************
+# Indexes (Performance Tuning)
+# *****************************************************************************
+
+CREATE INDEX idx_name ON table_name (column_name);             # Create a standard index to speed up queries
+CREATE UNIQUE INDEX idx_name ON table_name (column_name);      # Create a unique index (no duplicate values)
+SHOW INDEX FROM table_name;                                    # List all indexes on a specific table
+DROP INDEX idx_name ON table_name;                             # Remove an index from a table
+EXPLAIN SELECT * FROM table_name WHERE condition;              # Analyze how MySQL executes a query (Check index usage)
+
+# *****************************************************************************
+# Transactions (Data Integrity)
+# *****************************************************************************
+
+START TRANSACTION;                                             # Begin a new transaction
+COMMIT;                                                        # Save all changes made during the transaction
+ROLLBACK;                                                      # Undo all changes if an error occurs before commit
+SET AUTOCOMMIT = 0;                                            # Disable automatic commits for the current session
+SET AUTOCOMMIT = 1;                                            # Re-enable automatic commits after finishing manual transactions