SchemaSpy to visualise the DB schema design

Are you looking for very simple and lightweight tool that generates ER diagram from commonly used DBs. SchemaSpy tool will help you to understand all the relationships in DB schema. This week blog is about SchemaSpy tool.

About SchemaSpy:

SchemaSpy is a Java-based tool (requires Java 5 or higher) that analyzes the metadata of a schema in a database and generates a visual representation of it in a browser-displayable format. It lets you click through the hierarchy of database tables via child and parent table relationships as represented by both HTML links and entity-relationship diagrams. It's also designed to help resolve the obtuse errors that a database sometimes gives related to failures due to constraints. It’s free.

SchemaSpy uses JDBC's database metadata extraction services to gather the majority of its information, but has to make vendor-specific SQL queries to gather some information such as the SQL associated with a view and the details of check constraints. The differences between vendors have been isolated to configuration files and are extremely limited. Almost all of the vendor-specific SQL is optional.

Browse some sample pages generated by SchemaSpy. Note that this was run against an extremely limited schema so it doesn't show the full power of the tool.

SchemaSpy is a command line tool. If you are interested to work with GUI based tools. Try Its GUI tools using http://www.joachim-uhl.de/projekte/schemaspygui/

Running SchemaSpy

You run SchemaSpy from the command line:

java -jar schemaSpy.jar -t dbType -db dbName [-s schema] -u user [-p password] -o outputDir

More details to explore SchemaSpy can be found below:

http://schemaspy.sourceforge.net/

Happy Learning,

Nanjundan Chinnasamy