Computer Awareness Sample Questions

1. Database redesign is not terribly difficult if the:

database is structured.

database is well-designed.

database has no data.

database is relatively small.

Ans (3)

2. A regular subquery can be processed:

from the top down.

from the bottom up.

by nesting.

None of the above is correct.

Ans (2)

3. Which of the following SQL statements are helpful in database redesign?

Correlated subqueries only

EXISTS/NOT EXISTS expressions only

Both of the above are helpful

None of the above are helpful.

Ans (3)

4. Which is not true of a correlated subquery?

EXISTS/NOT EXISTS is a form of a correlated subquery.

The processing of the SELECT statements is nested.

They can be used to verify functional dependencies.

They are very similar to a regular subquery.

Ans (4)

5. The EXISTS keyword will be true if:

any row in the subquery meets the condition only.

all rows in the subquery fail the condition only.

both of these two conditions are met.

neither of these two conditions is met.

Ans (1)

6. The NOT EXISTS keyword will be true if:

any row in the subquery meets the condition.

all rows in the subquery fail the condition.

both of these two conditions are met.

neither of these two conditions is met.

Ans (2)

7. How can you find rows that do not match some specified condition?

EXISTS

Double use of NOT EXISTS

NOT EXISTS

None of the above is correct.

Ans (2)

8. Before any changes to database structure are attempted one should first:

clearly understand the current structure and contents of the database only.

test any changes on a test database only.

create a complete backup of the operational database only.

All of the above should be done.

Ans (4)

9. The process of reading a database schema and producing a data model from that schema is known as:

data modeling.

database design.

reverse engineering.

None of the above is correct.

Ans (3)

10. The data model that is produced from reverse engineering is:

1. a conceptual model.

2. an internal model.

3. a logical model.

4. None of the above is correct.

Ans (4)

11. A tool that can help designers understand the dependencies of database structures is a:

dependency graph.

data model.

graphical display.

None of the above is correct.

Ans (1)

12. How many copies of the database schema are typically used in the redesign process?

One

Two

Three

Four

Ans (3)

13 Which SQL-92 standard SQL command can be used to change a table name?

RENAME TABLE

CHANGE TABLE

ALTER TABLE

None of the above is correct.

Ans (4)

14.What SQL command can be used to add columns to a table?

MODIFY TABLE TableName ADD COLUMN ColumnName

MODIFY TABLE TableName ADD ColumnName

ALTER TABLE TableName ADD COLUMN ColumnName

ALTER TABLE TableName ADD ColumnName

Ans (3)

15. What SQL command can be used to delete columns from a table?

MODIFY TABLE TableName DROP COLUMN ColumnName

MODIFY TABLE TableName DROP ColumnName

ALTER TABLE TableName DROP COLUMN ColumnName

ALTER TABLE TableName DROP ColumnName

Ans (3)

16. To drop a column that is used as a foreign key, first:

drop the primary key.

drop the table containing the foreign key..

drop the foreign key constraint.

All of the above must be done.

Ans (3)

17. Which of the following modifications may not succeed?

Changing a column data type from char to date

Changing a column data type from numeric to char

Both of the above actions should succeed.

Neither of the above actions will succeed.

Ans (1)

18. What SQL command will allow you to change the table STUDENT to add the constraint named GradeCheck that states that the values of the Grade column must be greater than 0?

ALTER TABLE STUDENT ALTER CONSTRAINT GradeCheck (Grade > 0);

ALTER TABLE STUDENT ADD CONSTRAINT GradeCheck (Grade > 0);

ALTER TABLE STUDENT ADD CONSTRAINT GradeCheck CHECK (Grade > 0);

None of the above is correct.

Ans (3)

19. Changing cardinalities in a database is:

a common database design task.

a rare database design task, but does occur.

a database design task that never occurs.

is impossible to do, so a new database must be constructed and the data moved into it.

Ans (1)

20. Because of the importance of making data model changes correctly, many professionals are __________ about using an automated process for database redesign.

optimistic

skeptical

ambivalent

None of the above is correct.

Ans (2)