This is a sample output of schemaspy, which i took from their homepage.
Today i analyzed a database for reporting purpose, but there were so many tables and it was a bit opaque which table has releationships to which other table(s) and so i goggled a bit and found a tool called SchemaSpy, which comes as a jar File and is startable on the command line.
java -jar schemaSpy_5.0.0.jar -t orathin -host
Realy cool and easy peasy to use.
You can not edit the output, but in my case its ok to have an ER-Diagram of this database.