Database The class of databases. Table The class of database tables. Column The class of database columns. Column and PK This Column is (part of) a Primary Key. Varchar2 The Datatype VARCHAR2, known from Oracle Databases: a 1 - 2000 character Text. Long The Datatype LONG, known from Oracle Databases: a datastore up to 2 GB. Date The Datatype DATE, known from Oracle Databases: stores time and date information. Number The Datatype NUMBER, known from Oracle Databases: a 40 digit floating point. BLOB The Datatype BLOB (Binary Large Object), known from Oracle Databases: stores up to 4 GB. hasTable A Database has a set of Tables. hasColumn A Table has a set of Columns. isOfType A Table Column has a Dataype references A Foreign Key Column references a Table with a Primary Key.