FillDB is a free tool that lets you quickly generate large volumes of custom data in MySql format to use in testing software and populating databases with random data.

Open Source cross-platform SQL Editor and Database Manager. Use Beekeeper Studio to query and manage your relational databases, like MySQL, Postgres, SQLite, and SQL Server. Available for Windows, Mac, and Linux.

Vitess is a database clustering system for horizontal scaling of MySQL.

Free multi-platform database tool for developers, SQL programmers, database administrators and analysts. Supports all popular databases: MySQL, PostgreSQL, MariaDB, SQLite, Oracle, DB2, SQL Server, Sybase, MS Access, Teradata, Firebird, Derby, etc.

pg_chameleon is a MySQL to PostgreSQL replica system written in Python 3. The tool can connect to the mysql replication protocol and replicate the data changes in PostgreSQL. Whether the user needs to setup a permanent replica between MySQL and PostgreSQL or perform an engine migration, pg_chamaleon is the perfect tool for the job.

Metabase is the easy, open source way for everyone in your company to ask questions and learn from data.

Phinx makes it ridiculously easy to manage the database migrations for your PHP app. In less than 5 minutes you can install Phinx and create your first database migration. Phinx is just about migrations without all the bloat of a database ORM system or framework.

Query Editor: think of JS Fiddle for SQL queries. It's your way to share data in the organization in an open way, by sharing both the dataset and the query that generated it.
Visualizations: once you have a dataset, you can create different visualizations out of it.
Dashboards: combine several visualizations into a single dashboard.

Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is damn vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, help web developers better understand the processes of securing web applications and aid teachers/students to teach/learn web application security in a class room environment.

Convert MySQL Queries to MongoDB Syntax

A tutorial covering SQL indexing and SQL tuning for developers: avoiding unnecessary details about database internals.

SQL indexing is the most effective SQL tuning method and requires the same care as schema design yet it is often neglected during development. Use The Index, Luke explains SQL indexing from the source code perspective—covering ORM tools like Hibernate and Doctrine.

MySQLTuner is a script written in Perl that will assist you with your MySQL configuration and make recommendations for increased performance and stability.

MySQL database management tool

Web based MySQL administration

Samples are provided to allow reader to get basic idea of a potential SQL Injection attack and almost every section includes a brief information about itself.

WWW SQL Designer allows users to create database designs, which can be saved/loaded and exported to SQL scripts. Various databases and languages are supported. Ability to import existing database design.

Extremely lightweight alternative to heavy phpMyAdmin for quick and easy access MySQL databases.