Question

You need to ensure that the last_name column does not contain null values. Which type of constraint should you define on the last_name column?

Answer 1

Answer:

CHECK

PRIMARY KEY

UNIQUE

NOT NULL (*)

Answer 2

column level constraint has scope only to the column it is defined on. A table level constraint can see every column in the table. That is the major difference between the two - that of "scoping". Any column level constraint (exception: not null) can be expressed at the table level - but the opposite is not true.