To install SQLite3 in windows you require not only the gem but a DLL files in your system PATH (or in your windows/system32 folder).

To obtain the DLL, go to: http://www.sqlite.org/download.html

I always believe that DLLs belong in the windows/system32 folder but as long as you put yours somewhere where your PATH environment variable points to, you should be fine.

Installing/Updating the SQLite3 Gem

Normally to install the gem you’d call gem install sqlite3-ruby and it would do everything automatically but if you try it (as of today) it will give you the following error:

C:>gem install sqlite3-ruby
Building native extensions. This could take a while...
ERROR: Error installing sqlite3-ruby:
ERROR: Failed to build gem native extension.

c:/ruby/bin/ruby.exe extconf.rb install sqlite3-ruby
checking for fdatasync() in rt.lib... no
checking for sqlite3.h... no

nmake
'nmake' is not recognized as an internal or external command,
operable program or batch file.

Gem files will remain installed in
c:/ruby/lib/ruby/gems/1.8/gems/sqlite3-ruby-1.2.4 for inspection.
Results logged to
c:/ruby/lib/ruby/gems/1.8/gems/sqlite3-ruby-1.2.4/ext/sqlite3_api/gem_make.out

As not helpful as that error message is, it turns out that the new version of sqlite3-ruby doesn’t have a win32 version (which is needed for it to install/function correctly). So all you have to do is specify an older version of sqlite3.

To install a older version of a gem, run:

gem install --version 1.2.3 sqlite3-ruby

Now you’re all set to go!

Once sqlite3 is installed and you try to update the rest of your gems calling gem update, it will fail because (as of September 8th) sqlite3-ruby doesn’t have a win32 version of the 1.2.4 gem. To get around this, remove the sqlite3-ruby gem (gem uninstall sqlite3-ruby), then call gem update and then reinstall the gem by calling gem install –version 1.2.3 sqlite3-ruby.

SOURCE:

The most helpful site online that helped me figure this out was: http://www.ruby-forum.com/topic/164116

UPDATE:

I just tired updating the gems myself and had to uninstall sqlite3-ruby (it seems as of October 21st, 2008, they still haven’t fixed the issue!) and I copied the command of my own blog to find it doesn’t work. Not sure if it’s just firefox or wordpress but the problem is in the way the page is rendered, the “- – version” has a double dash (without the space) but the browser changes the html and makes it one dash. So I attempted to put it in a different format. So for those who had issues before, you can now copy the code above and just make sure that the version has a double dash in front of it.