|A database is supposed to store data. A data object is
a storage space holding values or information which can be identified by
name-type or data identifier.
Data type: The data type like integer, double, float, char , are fundamental data types. The class, struct , pointers, and enum are derived data types. The scalar data, like pointer and arithmatic data type, contains one single data value where as aggregate types, like arrays, struct, would have multiple values.
SQL and various programmatic interfaces and languages, including PL/SQL, Java, Oracle Call Interface, Pro*C/C++, OO4O, and C# have been enhanced with extensions to support Oracle objects. The result is an object-relational model that offers the intuitiveness and economy of an object interface while preserving the high concurrency and throughput of a relational database.
|Aggregate data types
|UML distinguishes two kind of aggregation, simple aggregation and composed aggregation.|
|Simple Aggregation: is a logical aggregation where elimination of one participants will not eliminate the this logical association or other participants. The simple aggregation does not imply any restriction over the other part. Here teacher to departments a simple aggregation, teacher block ( e.g. online courses) can be dropped and recreated without affecting the departments.|
|Composite or Composed-Aggregation:
is a special kind of aggregation in which the parts are physically
bonded as a whole unit, and a part of this aggregation, lives and
dies with its whole. Here the existence of student block is must to the
teacher block. The elimination of student block, also eliminate teacher
Composition implies a common ownership, where as an aggregation is a mere relationship.