What are good resources on data modelling for business intelligence? We are a SaaS startup offering purchase &amp; procurement solutions. The data model for operational transactions has been created (relational DB). We also want to offer analytics on those transactions to decision makers but using ad hoc queries to get this data out of the existing tables would be inefficient. What resources are out there on data modelling for business intelligence / data warehousing?
I recommend the Data Warehousing Toolkit by Ralph Kimball.  This is a solid book on dimensional modeling and provides many "soup to nuts" case studies.