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Cisy 221:Database Systems Question Paper

Cisy 221:Database Systems

Course:Computer Science

Institution: Kenya Methodist University question papers

Exam Year:2015

END OF 1''st ''TRIMESTER 2015 (PT) EXAMINATION
FACULTY : COMPUTING & INFORMATICS
DEPARTMENT : COMPUTER SCIENCE
UNIT CODE : BBIT 232/CISY 221/BSIS 115
UNIT TITLE : DATABASE SYSTEMS
TIME : 2 HOURS

INSTRUCTIONS:

Answer question One and any other Two questions.

Question One (30 marks)

Citing an example, define the following terms as used in databases

Desired attribute.

(2 marks)

Cardinality
Weak relationship
Give the importance of entity and referential integrity in a database. (4 marks)

Differentiate between logical independence and physical independence.

(4 marks)

What are the potential costs of implementing a database system?

(4 marks)

What is a recursive relationship? Give an example

(3 marks)

Outline the conditions that have to be met before database is said to is 3NF

(3 marks)

Briefly describe the two categories of SQL

(4 marks)

Describe two advantages of the database approach over the file-system approach.

(2 marks_

Question Two (15 marks)

Distinguish between:
Candidate key and super key
DMBS and database

Write the SQL code that will create the table structure for a table named EMPLOYEE

(3 marks)

Figure 1.

Attribute (field name) Data declaration
EMP_NUM CHAR(3)
EMP_LNAME VARCHAR(15)
EMP_FNAME VARCHAR(15)
EMP_INITIAL CHAR(1)
EMP_HIREDATE DATE
JOB_CODE CHAR(3)

Write the SQL code to enter the first two rows for the table (undo)

Figure 2.
EMP_NUM EMP_LNAME EMP_FNAME EMP_INITIAL EMP_HIREDATE JOB_CODE
101 News John G 08-NOV-00 502
102 Senior David H 12-JUL-89 501
103 Arbough June E 01-DEC-96 500
104 Ramoras Anne K 15-NOV-87 501
105 Johnson Alice K 01-FEB-93 502
106 Smithfield William 22-JUN-04 500
107 Alonzo Maria D 10-OCT-93 500
108 Washington Ralph B 22-AUG-91 501
109 Smith Larry W 18-JUL-97 501

Assuming the data shown in the EMPLOYEE table has been entered. Write the SQL code that will list all attributes for a job code 50z

(2 marks)

Write the SQL code to change the job code to 50 for the person whose employee number (EMP¬¬¬_NUM) is 107.

(2 marks)

Question Three (15 marks)

Define the concept of partial dependency and transitive dependency.

(4 marks)

To keep track of office furniture, computers, printers and so on, the founder company uses the table structure shown in Table below:

Figure 3.
ATTRIBUTE NAME SAMPLE VALUE SAMPLE VALUE SAMPLE VALUE
ITEM ID 231134-678 342245-225 254668-449
ITEM LABEL HP Deskjet 895Cse HP Toner DT Scanner
ROOM _NUMBER 325 325 123
BLDG_CODE NTC NTC CSF
BLDG_NAME Nottooclear Nottoclear Canseefar
BLDG_MANAGER I.B. Rightonit I.B. Rightonit May B. Next

Given that information, write the relations scheme and draw the dependency diagram make sure that you label the transitive and/or partial dependencies

(6 marks)

Using the answer is (i) above with the relational scheme and create a set of dependency diagrams hat meet 3NF requirements.

(5 marks)

Question Four (15 marks)

Describe and characteristic the skills desired for a DBA

(6 marks)

State an ERD based on the Crow’s foot notation, using the following requirements:

(9 marks)

An INVOICE is written by a SALESREP. Each sales representative can write many invoices but each invoice is written by a single sales representative.
The INVOICE is written for a single CUSTOMER. However, each customer can have many invoices.
An INVOICE can include many detail lives (LINE), each of which describes one product bought by the customer.
The product information is stored in a product entity
The product’s vendor information is found in a VENDOR entity.

Cisy 221:Database Systems Question Paper

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