Let's say you have a massive database and invested thousands of hours work with millions of records across many tables - No problem! Directus can be installed into the same database. You will need to make sure Directus has full privilages on the database. I get this might concern many of you but rest assured, the only tables created during the installation are prefixed with directus_tablename.
Directus can be installed into an existing database even if include data. The application will create the necessary system tables and do it's best to visually represent your data through the web interface. From here you can change how your data is presented and if you intend for users to contribute through Directus, you can configure how more data can be inserted for each column.
Once installed and logged into your nice new interface, you'll notice your collections are empty. Don't worry, nothing has been deleted. You need to go into the Data Modals under Settings, then you'll see all you tables there.
Your next descision is which tables will be managed by Directus.
When Directus manages a table as a collection, this means you can veiw the data through the Directus platform including display options, input interfaces, version control, data export and data sharing. It's very powerful.
You can still add data directly into the database of a managed table however, you wont benefit from the built in version control. Instead, I encourage you to use the Directus API instead.
Not a problem. Directus supports relational tables, the tricky part is setting it up. Normally Directus will automatically set up the table structure for you when linking to tables together. However, when we have an existing relation table, it means manually naming the relation table and fields.
It's perfectly safe to install Directus in an existing database. If you have a complicated database schema, it may be worth setting up a copy to experiment with and experience the Directus platform.