For a database application, conceptual design methods such as fact-oriented modelling and entity-relationship modelling are commonly used to specify a conceptual schema, which may then be mapped to a structure in a chosen data model (e.g. a relational database schema). Since conceptual data models support a rich variety of constraints, and these constraints may impact on one another, the task of ensuring mat the constraints expressed in a conceptual schema are consistent is non-trivial. Moreover, because different constraint patterns may be equivalent, some optimization may be needed to select the best constraint pattern for explicit assertion. With reference to conceptual schemas expressed in FOrML (an enhanced version of NIAM) mis paper discusses metarules for strong satisfiability and constraint preference, and outlines an efficient algorithm for validating four main types of constraints. Complexity analyses and benchmarks of the implemented algorithm are included.