6. A computer-implemented method, comprising: receiving a calculation rule presented in an expression language and specifying one or more functions, the expression language allowing for each of a plurality of functions performable on a plurality of different platforms to be expressed using a common syntax; wherein the different platforms comprise: 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; identifying a selected platform on which the calculation rule is to be executed; resolving the calculation rule to attributes of a data model in the selected platform to apply the calculation rule to the data model; wherein resolving 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; 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; executing the calculation rule by performing the one or more functions specified in the calculation rule; and reporting the results from executing the calculation rule.
6. A computer-implemented method, comprising: receiving a calculation rule presented in an expression language and specifying one or more functions, the expression language allowing for each of a plurality of functions performable on a plurality of different platforms to be expressed using a common syntax; wherein the different platforms comprise: 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; identifying a selected platform on which the calculation rule is to be executed; resolving the calculation rule to attributes of a data model in the selected platform to apply the calculation rule to the data model; wherein resolving 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; 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; executing the calculation rule by performing the one or more functions specified in the calculation rule; and reporting the results from executing the calculation rule. 8. The computer-implemented method of claim 6 , wherein the expression language provides for the calculation rule to include one or more parameters solicited from a user when the calculation rule is applied to the data model.