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I am developing this application with an Oracle database. I haven't been documenting the data model, but now an auditor wants to have an entity relationship diagram of my database. There are many tables and creating the ERD in visio manually is out of the question.

I know Toad has Database > Export ER Diagram option, but the result is not exactly presentable because of ugly layout and difficult to edit. Do you know an alternative way which can create a presentable ER diagram? Preferably it will be nice if the resulting diagram is editable and also if the tool is free.

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up vote 6 down vote accepted

Have you got access to Microsoft Visio?

If you can get an ODBC connection to your Oracle DB then you can use Visio to scan the database. It will display all the entities, relationships, etc.

Have a look at this on Stack Exchange

Hope that helps

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Oracle has a free tool SQL Developer that has can presumably reverse engineer an Oracle database.

If the database isn't too large then you could possibly use a tool like DbVisualizer (which is either free or low cost depending on the version). You can only diagram one schema at a time and results aren't directly editible (it's really more of an exploration tool) but you can save the diagram as GML and edit it with a tool such as yEd (which is a free download) (Note that you will need to edit the gml file slightly before bringing it into yEd by replacing all instances of 'customconfiguration "SimpleRectangle"' with 'type "rectangle"').

Note that SQL Developer, DbVisualizer, and yEd are all cross platform tools so you can use them on any system that has Java installed.

Update -- I just tried reverse engineering (154 tables) using SQL Developer. It appears to work reasonably well but it isn't going to win any beauty contests...

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There's an open source project in SourceForge called Schema Spy ( which generates HTML schema reports, including ERDs:

On the good side this tool is free, however the diagrams are not editable.

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can this generate ER diagram from sql dump file? – user2720864 Jul 9 '15 at 10:37

SchemaCrawler is a free tool that can generate database diagrams for Oracle, with help from GraphViz. Actually, SchemaCrawler generates GraphViz DOT files, which are plain text files that are editable.

Sualeh Fatehi, SchemaCrawler

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I would suggest you to try a free tool called Oracle SQL Developer Data Modeler.

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You are using the export graphics feature in Toad but you should instead use the print feature, but instead just printing it, print it to PDF. This will give you non-blurry ER-diagrams.

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Once, when I was truly desperate for an ER diagram of an Oracle database, I used MS Access, and the relationship diagram tool inside it. I created table links from an Access DB to the Oracle tables, and defined the references inside Access.

I then cranked up the relationship diagram, and moved the boxes around until it was at least presentable. This won't win any beauty contests either, but it's a workaround.

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