Adbms 16 object definition language
- 1. Advance Database Management Systems:16 Object Definition Language Prof Neeraj Bhargava Vaibhav Khanna Department of Computer Science School of Engineering and Systems Sciences Maharshi Dayanand Saraswati University Ajmer
- 2. Slide 21- 2 Object Definition Language • ODL supports semantics constructs of ODMG • ODL is independent of any programming language • ODL is used to create object specification (classes and interfaces) • ODL is not used for database manipulation
- 3. Slide 21- 3 ODL Examples (1) A Very Simple Class • A very simple, straightforward class definition – (all examples are based on the university schema presented in Chapter 4): class Degree { attribute string college; attribute string degree; attribute string year; };
- 4. Slide 21- 4 ODL Examples (2) A Class With Key and Extent • A class definition with “extent”, “key”, and more elaborate attributes; still relatively straightforward class Person (extent persons key ssn) { attribute struct Pname {string fname …} name; attribute string ssn; attribute date birthdate; … short age(); }
- 5. Slide 21- 5 ODL Examples (3) A Class With Relationships • Note extends (inheritance) relationship • Also note “inverse” relationship class Faculty extends Person (extent faculty) { attribute string rank; attribute float salary; attribute string phone; … relationship Dept works_in inverse Dept::has_faculty; relationship set<GradStu> advises inverse GradStu::advisor; void give_raise (in float raise); void promote (in string new_rank); };
- 6. Slide 21- 6 Inheritance via “:” – An Example interface Shape { attribute struct point {…} reference_point; float perimeter (); … }; class Triangle: Shape (extent triangles) { attribute short side_1; attribute short side_2; … };
- 7. ODL: CLASSES & ATTRIBUTES
- 9. ODL: RELATIONSHIPS & INVERSE RELATIONSHIPS
- 10. ODL: MULTIPLICITY OF RELATIONSHIPS
- 11. ODL: METHODS
- 12. ODL: INHERITANCE
- 13. ODL: INSTANCES & KEYS
- 14. Assignment • What is Object Definition Language • Explain the concept of Relationships and inverse relationship in ODL