Fabricio Carella

This plugin will allow you to execute any type of SQL query into the WordPress’s DB connecting through the driver provided by the MySQLi extension without the need to use another tool like phpMyAdmin.
It also gives you the ability to export the results in a CSV format file.
In order to access this plugin’s admin page (Tools -> Run SQL Query), your account needs to have the <code>install_plugins</code> capability, that means a Super Admin in the multi-site installation or an Admin in a single site.
Feel free to contribute: 
https://github.com/Sefirost/run-sql-query
Use on you own risk. Under no circumstances will the Author of this plugin assume responsibility or liability for any damages or destructive effects on the database resulting from the queries executed using this tool.

Run SQL Query

Run SQL Query is a simple plugin to quickly execute any type of SQL query into the WordPress's DB and export the results in a CSV format file.

Olar Marius

Justin Watt

Instead of needing a tool like <a href="http://www.phpmyadmin.net/home_page/index.php" rel="nofollow ugc">phpMyAdmin</a> 
or the mysql command line client to view and modify your WordPress database, 
the SQL Executioner allows you to run arbitrary SQL queries against your 
WordPress database from within the Admin. In many cases this allows you to bypass 
the inherent limitations of the WordPress Admin interface, and use the full expressive 
power of SQL to analyze and update your blog’s database.
To use simply install and visit the Tools > SQL Executioner page.
If you’re interested in contributing to the code behind this plugin, it’s also hosted on GitHub: 
https://github.com/justincwatt/wp-sql-executioner

SQL Executioner

This plugin seems to me simple but very useful.

Simple and efficient

I use this plugin on a daily basis to run quick queries in the database while developing. Very very helpful!!!

Amazing Tool

Execute arbitrary SQL queries against your WordPress database from the Admin.

Run SQL Query vs SQL Executioner