Consider the foreign-key constraint from the 'dept name' attribute of 'instructor' to the 'department' relation. Give examples of inserts and deletes to these relations that can cause a violation of the foreign-key constraint.

Inserting a tuple:

(10111, Ostrom, Economics, 110,000)

into the instructor table, where the department table does not have the

department Economics, would violate the foreign key constraint.

• Deleting the tuple:

(Biology, Watson, 90000)

from the department table, where at least one student or instructor

tuple has dept name as Biology, would violate the foreign key constraint.

employee (person name, street, city)

works (person name, company name, salary)

company (company name, city)