Description of the example database: Apartments for rent http://db.cs.helsinki.fi/~laine/epl.html
Contents of the tables in the database: http://www.cs.helsinki.fi/u/laine/sqlex/tables.html
Samples of SQL queries, part I: http://www.cs.helsinki.fi/u/laine/tikape/harkka_ans.html
Samples of SQL queries, part II: http://www.cs.helsinki.fi/u/laine/tikape/h2t.html