1Z0-006 Database Objects and Constraints

Question 1

Which Oracle constraint ensures that a column value cannot be NULL?

Accepted Answer

NOT NULL

Answer

UNIQUE

Answer

CHECK

Answer

DEFAULT

Question 2

Which constraint ensures that each value in a column is unique across the table but still allows NULL values?

Accepted Answer

UNIQUE

Answer

PRIMARY KEY

Answer

NOT NULL

Answer

CHECK

Question 3

What is the primary purpose of a FOREIGN KEY constraint in Oracle Database?

Accepted Answer

To enforce referential integrity between two tables

Answer

To ensure all values are distinct within a column

Answer

To limit the range of values in a column

Answer

To prevent NULL values in a column

Question 4

Which constraint type allows you to specify a condition that every row's column value must satisfy?

Accepted Answer

CHECK

Answer

NOT NULL

Answer

UNIQUE

Answer

FOREIGN KEY

Question 5

Which statement about the PRIMARY KEY constraint is correct?

Accepted Answer

A PRIMARY KEY uniquely identifies each row and does not allow NULLs

Answer

A table can have multiple PRIMARY KEY constraints

Answer

PRIMARY KEY columns allow NULL values

Answer

PRIMARY KEY constraints can only be defined at the column level

Question 6

What is a composite primary key in Oracle Database?

Accepted Answer

A primary key made up of two or more columns

Answer

A primary key that references multiple tables

Answer

A primary key that allows NULL values in one column

Answer

A primary key created automatically by Oracle

Question 7

When a FOREIGN KEY constraint with ON DELETE CASCADE is defined, what happens when a parent row is deleted?

Accepted Answer

The child rows are automatically deleted

Answer

The deletion is rejected if child rows exist

Answer

The child rows are set to NULL

Answer

The child rows are moved to an archive table