In ontology-based data access the users access relational databases (RDBs) via ontologies that mediate between the users and the data. Ontologies are connected to data via declarative ontology-to-RDB mappings that relate each ontological term to an SQL query. KeywDB facilitates construction of ontology-to-RDB mappings in an interactive fashion. In KeywDB users provide examples of entities for classes that require mappings and the system returnes a ranked list of such mappings. In doing so KeywDB relies on techniques for keyword query answering over RDBs.