Tools for Generating Mock Data? [closed]

I'm looking for recommendations of a good, free tool for generating sample data for the purpose of loading into test databases. By analogy, something that produces "lorem ipsum" text for any RDBMS. Features I'm looking for include:

• Flexibility to generate data for an existing table definition.
• Ability to generate small and large data sets (> 1 million rows or more).
• Generate in SQL script format (INSERT statements) or else in a flat file format suitable for bulk import (which is usually faster).
• A command-line interface for easy scripting.
• Extensible, open source, written in a dynamic language (these are nice-to-haves, not strong requirements).

PS: I did search for a duplicate question on StackOverflow, but I didn't find one. If there is one, I'll be grateful to get a pointer to it.

Thanks for the great responses everyone! I should amend my requirements that I use Mac OS X as my primary development environment, not Windows (though I did say command-line interface is desirable, and that practically rules out Windows). The Windows-specific suggestions will no doubt be useful to other readers of this question, though, so thanks.

Here is my conclusion:

• GenerateData:
  • PHP web app interface, not command line
  • limited to generating 200 records (or pay $20 for license to generating 5,000 records)
• RedGate SQL Data Generator
  • not free, price $295
  • requires Windows, .NET, SQL Server
• Visual Studio 2008 Database Edition
  • requires Windows
  • requires costly MSDN or ISV subscription
• Banner Datadect
  • not free, price $595
  • requires Windows (?)
  • no support for MySQL (?)
  • GUI, not command line or scriptable
• Ruby Faker gem
  • way too slow to use ActiveRecord for bulk data load
• Super Smack
  • chiefly a load-testing tool, with a random data generator built in
  • pretty simple to use nevertheless
  • overall a good runner-up tool
• Databene Benerator
  • best solution for my needs
  • XML scripts, compatible with DbUnit
  • open source (GPL) Java code
  • command-line usage
  • access many databases directly via JDBC

Take a look at databene benerator, a test data generator that looks close to your requirements.

• it can generate data for an existing table definition (or even anonymize production data)
• it can generate larges data set (unlimited size)
• it supports various input (CSV, Flat Files, DBUnit) and output format (CSV, Flat Files, DBUnit, XML, Excel, Scripts)
• it can be used on the command line or through a maven plugin
• it's open source and customizable

I would give it a try.

BTW, a list of similar products is available on databene benerator's web site.

This looks quite promising: generatedata.com. Open-source, has lots of built-in data types.

There are several others listed here: Test (Sample) Data Generators. I don't have experience with any of them, but a few on that list look like they could be pretty decent.

Try http://www.mockaroo.com

This is a tool my company made to help test our own applications. We've made it free for anyone to use. It's basically the Forgery ruby gem with a web app wrapped around it. You can generate data in CSV, txt, or SQL formats. Hope this helps.

I know you said you were looking for a free tool, but this is one case where I would suggest that spending $295 will pay you back quickly in time saved. I've been using the RedGate tool SQL Data Generator for the last year and it is, to be short, an awesome tool. It allows for setting dependencies between columns, generates realistic data for business objects such as phone numbers, urls, names, etc. I can honestly state that this tool has paid for itself time and time again.