Metric values can be used in order to compare and evaluate software entities, find defects, and predict quality. For some programming languages there are much more known metrics than for others. It would be helpful, if one could use existing metrics in order to find candidates for new metrics. A solution is based on an observation that it is possible to specify abstract syntax of a language by using a metamodel. In the paper a metrics development method is proposed that uses metamodel-based translation. In addition, a metamodel of a language helps us to find the extent of a set of metrics in terms of that language. That allows us to evaluate the extent of the core of a language and to detect possible quality problems of a set of metrics. The paper contains examples of some candidate metrics for object-relational database design, which have been derived from existing metrics.