1Z0-006 Database Objects and Constraints

Question 1

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

Accepted Answer

NOT NULL

Answer

The NOT NULL constraint prevents a column from accepting NULL values, ensuring every row has a value for that column.

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

The UNIQUE constraint ensures no two rows have the same non-NULL value in the constrained column, but unlike PRIMARY KEY, it permits NULL values.

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

A FOREIGN KEY constraint enforces referential integrity by ensuring values in the child table's column match existing values in the referenced parent table's primary key.

Question 4

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

Accepted Answer

CHECK

Answer

The CHECK constraint defines a condition that must evaluate to TRUE for every row, letting you restrict which values are accepted in a column.

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 PRIMARY KEY constraint combines NOT NULL and UNIQUE, ensuring the primary key column(s) uniquely identify each row and contain no NULL values.

(1Z0-006) Oracle Database Foundations Associate Practice Test

(1Z0-006) Oracle Database Foundations Associate Practice Test

1Z0-006 Database Objects and Constraints