Home > Query Language
A very important interface to database systems is the query API and the query language. Although object-oriented database systems sometimes do not support a dedicated query language, OOMEGA is convinced that it is crucial for comfortable data access.
Prior to exploring the query language, let's show the sample metamodel which is used throughout the whole chapter.
@entity (cid=1200) class Person
{
@attribute String firstname;
@attribute String lastname;
@attribute @notnull Natural yearOfBirth;
@attribute Address birthplace;
@association (foreign="children", mult="0..2") Set<Person> parents;
@association (foreign="parents") Set<Person> children;
@association (foreign="spouse") Person spouse;
}
@attribute (cid=1201) class Address
{
@attribute String street;
@attribute String city;
@attribute @notnull Natural zipCode;
@attribute String country;
}
Next chapter: Basic Concepts
