The size of agricultural databases continues to increase, and sources of information are growing more and more diversified. This is especially the case for databases dedicated to the traceability of agricultural practices. Some data are directly collected from the field using embedded devices; other data are entered by means of different computer-based applications. Once stored in the same database, all this information must be consistent in order to guarantee the quality of the data. This consistency issue is becoming a new challenge for agricultural databases, especially when complex data are stored (for instance georeferenced information). In order to achieve consistency in a database, a precise, formal specification of the integrity constraints is needed. Indeed, database designers and administrators need a language that facilitates the conceptual modeling of this type of constraint. In this chapter, we introduce the Object Constraint Language (OCL), using the example of an agricultural database for organic waste management. The example of a tool supporting OCL (the Dresden OCL Toolkit) and an overview of a spatial extension of the language will be also presented.