LÖSNINGSFÖRSLAG till DBTEK-tentan 13 januari 1999 (TDDB38)
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Det här är FÖRSLAG på lösningar.
Det kan finnas andra svar som också är riktiga.
Dessutom kan en del av de här svaren vara utförligare än vad som
behövs för full poäng på tentan.


Uppgift 1-4: Inga lösningar finns.

5. Similarities between E-R and Extended E-R:
   - Both models based on entities, relationships, attributes, 
     and cardinality constraints.
   Differences between E-R and Extended E-R:
   - E-E-R has inheritance (specialization)
   Similarities between OO and E-E-R:
   - Both have entities (classes), attributes, and inheritance.
   Differences between OO and E-R-R:
   - OO has methods
   - OO does normally not have relationships

6. QBE = Query By Example
   It is the most well known graphical relational query language 
   Used in e.g. MS Access.
   Queries are expressed as examples in table templates

   EMP         BOSS       EMP_2
   +------+    +------+   +------+
   | SSN  | +--| SSN  | +-| SSN  |
   | NAME | |  | SECR |-+ | NAME |
   | SAL  | |  +------+   | SAL  |
   | BOSS |-+             | BOSS |
   +------+               +------+

-----------------------------------------------------
Table:   EMP     EMP        EMP_2 
Field:   NAME    SAL        SAL
Sort:            descending
Show:     x      x
Criteria:                   <EMP.SAL

7. - OODB is persistent OO programming language
   - ORDB is relational DB weith OO concepts such as extensibility,
     inheritance, abstract datatypes, OIDs.
   - ORDB allows user defined abstract data types, indexes, operators to be defined.
   - ORDB allows SQL-like searches, while OODB mostly navigational.
   - OODB good when existing OO application needs persistence, there is not
     much concurrent access, little need for data independence,
     and limited demand for queries.
   - ORDB good when many applications need access to data concurrently.
   - ORDB good when advanced queries over DB needed.
   - Swizzling is a technique used in OODB to automatically convert disk-stored
     references between objects into main-memory adresses.

8. - A spatial database is a database where spacial objects, such as pictures,
     engineering elements, figures, etc., can be stored and searched efficiently.
   - A quad-tree is an indexing technique for 2D spatial objects where the bounding
     regions of the objects are origanized in a hieracrchy where there are 4
     subregions for each region (S, W, N, E).
   - An R-tree (region tree) is an indexing technique for spatial objects where
     the bounding regions are organized in a hierarchy of maximal bounding regions.
     The difference to the quand-tree is that the former always divides the
     regions into 4 fixed quadrants, while the R-tree fits optimized bounding
     regions over the subregions.