Zybook Week 4

Question 1

Unique Constraint

Answer 1

The UNIQUE constraint ensures that all column values are unique.

The UNIQUE constraint may be applied to a single column or to multiple columns. A constraint that is applied to a single column is called a column-level constraint. A constraint that is applied to multiple columns is called a table-level constraint.

Question 2

DEFAULT

Answer 2

specifies a default value
N

Question 3

NOT NULL

Answer 3

Says an attribute cannot be null