Database Redesign MCQs

Question 1

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

Accepted Answer

ALTER TABLE TableName ADD ColumnName

Answer

MODIFY TABLE TableName ADD COLUMN ColumnName

Answer

MODIFY TABLE TableName ADD ColumnName

Answer

ALTER TABLE TableName ADD COLUMN ColumnName

Question 2

The EXISTS keyword will be true if:

Accepted Answer

any row in the subquery meets the condition only.

Answer

all rows in the subquery fail the condition only.

Answer

both of these two conditions are met.

Answer

neither of these two conditions is met.

Question 3

Changing cardinalities in a database is:

Accepted Answer

a common database design task.

Answer

a rare database design task, but does occur.

Answer

a database design task that never occurs.

Answer

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

Question 4

The NOT EXISTS keyword will be true if:

Accepted Answer

all rows in the subquery fail the condition.

Answer

any row in the subquery meets the condition.

Answer

both of these two conditions are met.

Answer

neither of these two conditions is met.

Question 5

The data model that is produced from reverse engineering is:

Accepted Answer

None of the above is correct.

Answer

a conceptual model.

Answer

an internal model.

Answer

a logical model.

Question 6

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

Accepted Answer

drop the foreign key constraint.

Answer

drop the primary key.

Answer

drop the table containing the foreign key.

Answer

All of the above must be done.

Question 7

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?

Accepted Answer

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

Answer

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

Answer

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

Answer

None of the above is correct.

Question 8

Which is not true of a correlated subquery?

Accepted Answer

They are very similar to a regular subquery.

Answer

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

Answer

The processing of the SELECT statements is nested.

Answer

They can be used to verify functional dependencies.

Question 9

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

Accepted Answer

dependency graph.

Answer

data model.

Answer

graphical display.

Answer

None of the above is correct.