In this case, relationship lines between foreign keys. MySQL Workbench provides facilities for reverse engineering existing databases, and then creating an EER Diagram automatically. They are often created for existing databases, to clarify their purpose or document them. Want to generate random test data for MySQL for testing your application? FillDb is a free tool that allows you to create huge amount of database test data which can be customized to your needs simply by uploading your database schema. We normally ask for the table structure(s), the problematic query and sample data to be able to reproduce the problem and resolve it by modifying the query, table structure, or global/session variables. One of the common tasks requested by our support customers is to optimize slow queries.