This example shows how to use composite value types as data members in objects
and other value types, as element types in containers, and as base types for
other composite value types. It also shows how to use composite value type
data members in queries.

The example consists of the following files:

person.hxx
  Header file defining the 'basic_name', 'name_extras', and 'name' composite
  value types. It also defines the 'person' persistent class which use the
  'name' value type in one of its data members.

person-odb.hxx
person-odb.ixx
person-odb.cxx 
person.sql
  The first three files contain the database support code and the last file
  contains the database schema for the person.hxx header.

  These files are generated by the ODB compiler from person.hxx using the
  following command line:

  odb -d <database> --generate-schema --generate-query person.hxx
  
  Where <database> stands for the database system we are using, for example,
  'mysql'.

database.hxx
  Contains the create_database() function which instantiates the concrete
  database class corresponding to the database system we are using.

driver.cxx
  Driver for the example. It includes the person.hxx and person-odb.hxx
  headers to gain access to the 'person' class and the database support
  code for this class. It also includes database.hxx for the 
  create_database() function declaration.
    
  In main() the driver first calls create_database() to obtain the database
  instance. It then persists a 'person' object, loads it and updates its
  nickname and aliases which reside in a composite value type, then re-loads
  the object and prints its name to verify that the changes have been made
  persistent. Finally, the driver performs a database query which uses a
  data member from the composite value type in its criterion.  

To run the example we first need to create the database schema. Using MySQL
as an example, this can be achieved with the following command:

mysql --user=odb_test --database=odb_test < person.sql

Here we use 'odb_test' as the database login and also 'odb_test' as the
database name.

Once the database schema is ready, we can run the example (using MySQL as
the database):

./driver --user odb_test --database odb_test