Relational database management

New methods of relational database management are described, for example, to enable completion and checking of data in relational databases, including completion of missing foreign key values, to facilitate understanding of data in relational databases, to highlight data that it would be useful to add to a relational database and for other applications. In various embodiments, the schema of a relational database is used to automatically create a probabilistic graphical model that has a structure related to the schema. For example, nodes representing individual rows are linked to rows of other tables according to the database schema. In examples, data in the relational database is used to carry out inference using inference algorithms derived from the probabilistic graphical model. In various examples, inference results, comprising probability distributions each for an individual table cell, are used to fill missing data, highlight errors, and for other purposes.