Koha users have begun building a library of useful SQL statements for use in building Koha reports. It’s on the Koha Wiki. You can add your own or put in a request for a report you’d like to know how to do. If you’d like to contribute you can either register on the site or use OpenID to log in. If you’ve never edited a wiki before, be sure to check out the the Wiki’s help page on editing before you jump in.