Databases and Units of Measure

A serious impediment to the integrated use of databases across international boundaries, scientific disciplines and application areas is the use of different units of measure, e.g., miles or kilometers for distance, dollars or rupees for currency, and Btu or kWh for energy. Units of measure are not specified in the data definition language but associated by convention with values in the database. Inconsistent usage of values with different units cannot be checked atuomatically. Retrieval, storage, and manipulation of data values in units other than those associated with the values requires that the user perform the appropriate conversions. This process is inconvenient and error prone. These problems are illustrated by an international database example.