$(4$ points$)$ What does it mean to say that a table displays both entity integrity and referential

integrity? Explain$/$define each and give a specific example of each that is valid and a specific

example of each that is invalid or a violation.

$(4$ points$)$ Which relational algebra operators can be applied to a pair of tables that are not

union$-$compatible? Explain each using an example.

$(4$ points$)$ Given the two tables below, identify the best choice for primary key$($s$)$ and the

corresponding foreign key$($s$)$

EMPLOYEE

DEPARTMENT

$(4$ points$)$ What two conditions must be met before an entity can be classified as a weak

entity? Give an example.

$(4$ points$)$ What is a derived attribute? Give an example