Q1: Consider the below schema for a library database and write relational algebr

Question

Q1: Consider the below schema for a library database and write relational algebra expressions for the

Following

1. Author ( authorname, citizenship, birthyear)

2. Book (isbn, title, authorname)

3. Topic (isbn, subject)

4. Branch (libname, city)

5. Instock (isbn, libname, quantity)

1. Give all authors’ names born after 1940. [0.25 Point]

2. Give the names of libraries in Sydney. [0.25 Point]

3. Give the cities where each book is held. [0.25 Point]

4. Give the title of each book on the topic of either alcohol or drugs. [0.25 Point]

5. Give the title and author of each book of which at least two copies are held in a branch located in

Melbourne

Q2. What are the responsibilities of a DBA? If we assume that the DBA is never interested in running

his or her own queries, does the DBA still need to understand query optimization? Why? [1.5 Marks]

Q3: What are the drawbacks of using file system over database management system? [1 Marks]

Explanation / Answer

1. select authorname from Author where birthyear>1940;

2. select libname from Branch where city = 'Sydney';

3.

4. select title from Book, Topic where book.isbn=topic.isbn;

5. select title, authorname from book, instock, Branch where instock.quantity>=2 and book.isbn=instock.isbn and branch.city = 'Melbourne';

Q2 There are number of responsibilities of DBA some of them are as follows

(1) Creates and maintains all databases required for development, testing,
education and production usage.

(2) Performs the capacity planning required to create and maintain the
databases. The DBA works closely with system administration staff because
computers often have applications or tools on them in addition to the Oracle
Databases.

(3) Performs ongoing tuning of the database instances.

(4) Install new versions of the Oracle RDBMS and its tools and any other tools
that access the Oracle database.

(5) Plans and implements backup and recovery of the Oracle database.

Q3.

Following are the advantages of DBMS over Filesystem
Flexibility: Because programs and data are independent, programs do not have to be modified when types of unrelated data are added to or deleted from the database, or when physical storage changes.
• Fast response to information requests: Because data is integrated into a single database, complex requests can be handled much more rapidly than locating data separately. In many businesses, faster response means better customer service.
• Multiple access: Database software allows data to be accessed in a variety of ways (through various key fields), by using several programming languages (both3GL and nonprocedural4GL programs).
• Lower user training costs: Users often find it easier to learn such systems and training costs may be reduced. Also, the total time taken to process requests may be less, which would increase user productivity.
• Less storage: Theoretically, all occurrences of data items need be stored only once, thereby eliminating the storage of redundant data. System developers and database designers often use data normalization to minimize data redundancy.

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