In the Database Analysis Life Cycle, 'Testing and evaluation'



NAPIER UNIVERSITY

SCHOOL OF COMPUTING

FIRST DIET (SEMESTER TWO) EXAMINATION

SESSION 2000-2001

CO72010: DATABASE SYSTEMS

DATE : DURATION: 2 HOURS

START TIME:

EXAMINER:

MR. A. CUMMING

QUESTION PAPER DATA

Number of Pages - ELEVEN

Number of Questions - FORTY

Number of Sections - ONE

INSTRUCTIONS TO CANDIDATES

Answer ALL questions.

For each question select ONE from (a) to (e).

Answers must be entered on the answer sheet provided using a horizontal line.

A pencil must be used.

Append Answer Sheet to Question Paper.

PLEASE READ THE FULL INSTRUCTIONS BEFORE COMMENCING WRITING

Question 1- 5 concern the following database for a recruitment agency:

|job | |requirement |

|reference |employer |salary | |job |skill |

|01 |Napier |£20000 | |01 |Unix Admin |

|02 |GCHQ |£22000 | |01 |Oracle Admin |

|03 |Napier |£24000 | |02 |Unix Admin |

| | | | |02 |Number Theory |

The database currently holds three job vacancies. Two of the vacancies have specific skills requirements.

1. Choose the SQL statement which will return details of the jobs of interest to a candidate with experience of Unix Administration.

(a) SELECT * FROM job

WHERE reference='Unix Admin'

AND skill = 'Unix Admin';

(b) SELECT * FROM job, requirement

WHERE reference=job AND skill='Unix Admin';

(c) SELECT * FROM job

WHERE skill = 'Unix Admin';

(d) SELECT * FROM 'Unix Admin';

(e) SELECT 'Unix Admin' FROM job, requirement; (1)

2. A list of jobs together with a count of the required skills is needed. It is important that jobs such as 03, which has no skills specified, are included. Which of the following operations is most appropriate?

(a) CARTESIAN PRODUCT

(b) INNER JOIN

(c) INTERSECTION

(d) LEFT or RIGHT OUTER JOIN

(e) UNION (1)

3. Select the term which best describes the cardinality of the relationship: job to the requirement.

(a) many to many

(b) many to one

(c) one to many

(d) one to one

(e) some to many (1)

4. Which of the following show appropriate primary keys for the tables?

(a) job(reference, employer, salary) requirement(job, skill)

(b) job(reference, employer, salary) requirement(job, skill)

(c) job(reference, employer, salary) requirement(job, skill)

(d) job(reference, employer, salary) requirement(job, skill)

(e) job(reference, employer, salary) requirement(job, skill) (1)

5. The table requirement was created using the following SQL statement:

CREATE TABLE requirement (

job INTEGER,

skill VARCHAR(50),

FOREIGN KEY job REFERENCES job(reference));

Select the true statement concerning the requirements table.

(a) it cannot store a field with a NULL value for job

(b) it must be created BEFORE the job table

(c) the value 'Windows 2000 Admin' is NOT permitted for the skill attribute

(d) referential integrity checks will prevent invalid values for job

(e) referential integrity checks will prevent identical rows being inserted (1)

6. ( is the projection operator. ( is the selection operator. R is a relation.

Select the relational expression which could possibly return the following result:

|a |c |

|1 |2 |

|2 |3 |

(a) (a, c R

(b) (a ................
................

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