Simply and easily with SchemaSpy
It has never been easier to document you db. SchemaSpy analyzes your database with tables, columns, types and indexes. It even creates diagrams with relationships of your existing database.
The installation is super easy. You just have to download SchemaSpy and your database driver. Even Graphviz is no longer required. The configuration is really simple. Here I show a config.
You run the tool with java -jar schemaspy-6.1.0.jar -configFile config.properties. Then you get a HTML documenation and the diagrams look like this.
And a really cool trick is to integrate SchemaSpy in your CI/CD pipeline. I really like this tool.