ORDBMS Contd.
- List the names of all theaters showing Herbert films that are within 100 miles
Q2: SELECT N.theater name, N.theater address, F.title
FROM Nowshowing N, Films F, Countries C
WHERE N.film = F.filmno AND
overlaps (C.boundary, radius (N.theater address, 100)) AND
C.name = ‘Andorra’ AND ‘Herbert the Worm’ ? F.stars;
Query features:
- New operators for constructed types:??????????????????etc.
- Operators for reference types:
- User-defined methods
User-defined ADTs:
- Why ADT?
- The DBMS does not how an ADT data is stored, or how the methods work
- What does the DBMS know?
- what methods are available
- Input and output data types for the methods
- Encapsulation: hiding of ADT internals
- Object identity (Oid)
- DBMS generates a unique Oid for every object for its lifetime
- Oids for larger objects: tables
- Oids for smaller tables: tuples in a table
- reference type: theater ref(theater_t) in table Nowshowing