1. A system for creating a report in a spreadsheet, the system comprising: a central processing unit; and a memory encoding instructions that, when executed by the central processing unit, cause the central processing unit to create: a data source module programmed to identify tables associated with the spreadsheet; and a relationship module programmed to analyze the tables and identify related tables that have an undefined relationship, the relationship module defining a relationship for the related tables having the undefined relationship by using heuristics to automatically define the undefined relationship.