Any REBOL driver implementing the port API for databases (as used in REBOL Technologies' drivers) or in Softinnov's drivers will work. Non-standard drivers can be used too but won't benefit from Cheyenne's databases abstraction layer (you will need to open/close connections in your own code).
RSP and webapps provide a thin abstraction layer to access databases. This means, you don't have to care about opening, closing or re-opening databases connections. It is managed automatically by Cheyenne as long as you provide a definition in the configuration file using the databases? directive, in one of the sections (Globals, Hosts or webapp):
globals [ databases [ books mysql://user:pass/localhost/books ] ... ] domain.com [ ... databases [ books2 mysql://user:pass/localhost/books ] ... webapp [ ... databases [ books3 mysql://user:pass/localhost/books ] ] ]
: avoid using the same database definition name in different scopes as the inherited definitions can collide (needs a more accurate heritage support in the RSP engine).
You can add as much definitions as you need in the same databases block:
databases [ books mysql://user:pass/localhost/books admin mysql://root:pass/localhost/books sales oracle://user:pass/18.104.22.168/sales ... ]
Once defined, databases connections will be automatically opened on first SQL request. As Cheyenne relies on a pre-forked model for RSP scripts evaluation, the number of connections will scale up with the worker processes number, so you'll get a natural databases connection pooling for free!
The SQL queries are sent using a single function: DO-SQL that will take two arguments:
<% list: do-sql 'books "SELECT * FROM titles WHERE author='Kubrick'" %> <table> <tr><th>Title</th><th>Author</th><th>Year</th> <% foreach book list [ %> <tr> <td><%= book/1 %></td> <td><%= book/2 %></td> <td><%= book/3 %></td> </tr> <% ] %> </table>
Another example using parameters from the request:
<% unless invalid?: validate/full [author string! *][ list: do-sql 'books [ "SELECT * FROM titles WHERE author=?" request/content/author ] ] %>
This second form is what you should be using for securing query's arguments and avoiding SQL injection attacks.