Some sample exam 1 questions:
1. Briefly define the following terms:
Relation
Tuple
Integrity Constraint
Candidate Key
Primary Key
Foreign Key
System Catalog
Cursor
Entity, Entity set (in an ER model)
Relationship, Relationship set (in an ER model)
Key constraint (in an ER model)
Participation constraint (ER)
Weak entity (ER)
ISA hierarchy (ER)
Equi-Join
Natural Join
2. A music database contains information about Songs (identified by a unique
song id# and the title of the song), Bands (identified by a unique band name
and the number of members in the band), and Albums (identified by a unique
album id#, the title of the album, the number of songs on the album). Bands
sing Songs and produce Albums. Songs are parts of an Album. Draw an ER
diagram for each of the situations below:
- A Song may be part of more than one Album.
- A Song must be part of at least one Album.
- A Song appears on one and only one Album.
- Each Album must have at least one Song.
- A Band may sing more than one version of a Song, but each version must
appear on a different Album.
3. For the following relations (keys are shown with _s over the field name):
Student Class_Grade Class
___ ___ ___ ___
sname sid age gpa sid cid grade cid cdept cnum
-------------------- ------------- --------------
Ann 1 21 3.5 1 1 A- 1 CS 1621
Bob 2 19 3.4 1 2 A 2 BIOL 1011
Cal 3 20 2.6 2 1 B 3 ECE 1315
Dee 4 22 4.0 2 3 C
3 1 A
3 2 C
3 3 F
4 2 A
How would you design the following queries in Relational Algebra:
- The id#s of students who are 19 or 20.
- The student names (sname) of those students who have taken CS 1621.
- Students (names) who have taken a biology course or ECE course.
- Students (names) who have taken every course in Class.
- Students (names) who have received an A.
4. Answer question 3 using Domain Relational Calculus.
5. Answer question 3 using SQL.
For added practice, produce queries for exercises 5.1, 5.3 (answers can
be found on textbook web page).
6. Answer question 9 using QBE and skeletons as shown in class.
For added practice, produce queries for exercises 6.1.
7. Define the following operations in relational algebra:
Selection, Projection, Cross Product, Intersection, Union, Natural Join,
Division
How would you perform operations similar to these in Domain Relational
Calculus?
8. A SQL query may have five different clauses, a SELECT, FROM, WHERE,
GROUP BY and HAVING clause. Explain how each of these clauses works
and how they are evaluated in an SQL query. Give an example using
all five clauses.
9. How is a view defined in SQL? How are queries on views resolved? What
are some of the difficulties introduced with views?
10. What is meant by the term Buffer Replacement Policy? Give an example of
a buffer replacement policy and explain how this policy affects a DB.
Make sure to give advantages and disadvantages of your sample policy.
11. What are the advantages of using a variable length format for records in
a file. Give an example of how you might represent a record with four
fields, each of varying lengths.
12. Describe how each of the following page formats represents records:
* Variable length records with a slot directory
* Packed fixed length records
* Unpacked fixed length records with a bitmap
13. Three file storage mechanisms are heap files, sorted files and hashed files.
Give advantages and disadvantages of each. Make your answers specific with
respect to normal DB operations such a searching for a particular record,
or scanning all of the records, etc.
14. We discussed three representations for data entries in an index file.
Define these three possible representations and discuss advantages and
disadvantages of each representation and when they would be appropriate.
15. Define the following properties of indexes:
clustered versus clustered
dense versus sparse
primary versus secondary