Database Redesign(Ict-Basic)Q1

Which of the following modifications may not succeed?

1 Mark(s)

Neither of the above actions will 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

The data model that is produced from reverse engineering is:

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a conceptual model.
an internal model.
a logical model.
None of the above is correct.

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?

1 Mark(s)

ALTER TABLE STUDENT ALTER CONSTRAINT GradeCheck (Grade > 0);
ALTER TABLE STUDENT ADD CONSTRAINT GradeCheck CHECK (Grade > 0);
None of the above is correct.
ALTER TABLE STUDENT ADD CONSTRAINT GradeCheck (Grade > 0);

Changing cardinalities in a database is:

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is impossible to do, so a new database must be constructed and the data moved into it.
a rare database design task, but does occur.
a common database design task.
a database design task that never occurs.

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

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Two
One
Three
Four

Database redesign is not terribly difficult if the:

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database is well-designed.
database has no dat
database is structured.
database is relatively small.

The NOT EXISTS keyword will be true if:

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neither of these two conditions is met.
any row in the subquery meets the condition.
both of these two conditions are met.
all rows in the subquery fail the condition.

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

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MODIFY TABLE TableName ADD ColumnName
ALTER TABLE TableName ADD ColumnName
MODIFY TABLE TableName ADD COLUMN ColumnName
ALTER TABLE TableName ADD COLUMN ColumnName

Which is not true of a correlated subquery?

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EXISTS/NOT EXISTS is a form of a correlated subquery.
They can be used to verify functional dependencies.
They are very similar to a regular subquery.
The processing of the SELECT statements is nested

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

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test any changes on a test database only.
clearly understand the current structure and contents of the database only.
create a complete backup of the operational database only.
All of the above should be done.

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

1 Mark(s)

MODIFY TABLE TableName DROP ColumnName
MODIFY TABLE TableName DROP COLUMN ColumnName
ALTER TABLE TableName DROP COLUMN ColumnName
ALTER TABLE TableName DROP ColumnName

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

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database design.
reverse engineering.
data modeling.
None of the above is correct.

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

1 Mark(s)

None of the above is correct.
CHANGE TABLE
ALTER TABLE
RENAME TABLE

A regular subquery can be processed:

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by nesting.
None of the above is correct.
from the top down.
from the bottom up.

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

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drop the table containing the foreign key..
All of the above must be done.
drop the primary key.
drop the foreign key constraint.

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

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Correlated subqueries only
Both of the above are helpful
EXISTS/NOT EXISTS expressions only
None of the above are helpful.

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

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skeptical
ambivalent
optimistic
None of the above is correct.

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

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None of the above is correct.
graphical display.
dependency graph.
data model.

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

1 Mark(s)

None of the above is correct.
NOT EXISTS
EXISTS
Double use of NOT EXISTS

The EXISTS keyword will be true if:

1 Mark(s)

neither of these two conditions is met.
both of these two conditions are met.
any row in the subquery meets the condition only.
all rows in the subquery fail the condition only.

Database Redesign(Ict-Basic)Q1 : Question 1 of 20

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