In order to produce the example output table, the query on the relational database has to collect data from several database tables:

• If we want to find the name of the hometown of a given individual ABC, we have to
• find the references to that indidual (IndID) in the table of the residence episodes. There we can find a reference to his homestead (LocID). With this reference we can then
• find the homestead in the table of locations, where we can also get the name of the town.
• Since ABC has moved from Atown to Btown, he appears twice. Therefore we have to decide, which is the relevant residence episode, in order not to count the individual twice.