First order static database constraints are expressed as counterexamples, i.e., examples that violate the integrity of the database. Examples are data and as such they can be specified and stored as data, structured into database files for efficient search and retrieval, and enforced efficiently since enforcement reduces to data comparison between the constraints as example data and the database. To express all first order constraints as counterexamples, a new normal form for first order logic is created which, after some syntactic transformation, is amenable to storage in flat files, efficient search and retrieval, and efficient testing of models for validity. Such efficient management of constraints is likely to lead to the development of large constraint bases since constraints are useful in a variety of contexts such as:
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1. Maintaining data quality by catching in real time and eliminating a wide variety of errors ranging from typing mistakes to complex semantic violations,
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2. Enforcing data security by monitoring and authorizing access and modification to protected data,
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3. Implementing semantic data models within the simpler and better understood environment of relational model,
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4. Building model libraries where complex decision models can be described, stored, retrieved, and manipulated by using constraints that establish the logical relationships between their inputs and outputs.
