1. A computer-readable storage medium storing instructions executable by a computing system to perform a plurality of functions, comprising: receiving a calculation rule presented in a multi-platform expression language to be applied to a data model selected from different data models having different structures, the calculation rule being received by one or more of: retrieving the calculation rule from a store of previously-created calculation rules; and accepting user entry of the calculation rule; processing the calculation rule for application to the data model, including: responding to whether the calculation rule is data-driven, including: when the calculation rule is data-driven, determining a condition specified by the calculation rule and performing an action specified by the calculation rule based on the condition; and when the calculation rule is not data-driven, performing the action specified by the calculation rule; identifying a database platform supporting the data model; wherein the database platform is selected from a group of platforms comprising: a structured query language (SQL) platform that accesses a SQL database in which dimensions and data models are represented as a plurality of tables and a multi-dimensional database platform that accesses a multi-dimensional database in which the dimensions and the data models are stored in a multi-dimensional structure; preprocessing the calculation rule to adjust the calculation rule to operate based on a dimensionality of the data model; wherein preprocessing the calculation rule comprises determining when the calculation rule accesses more information than the data model provides and determining when to eliminate the calculation rule based on this determination; upon identifying one or more variables included in the calculation rule, resolving the variables in terms of the data model; and upon identifying one or more parameters included in the calculation rule, soliciting input for the parameters for use in applying the calculation rule to the data model by displaying a prompt to receive the parameters; and executing the calculation rule.