Writing Homework Help

Disc 1: How can the key and foreign key constraints be enforced by the DBMS? Is the enforcement technique you suggest difficult to implement? Can the constraint checks be executed in an efficient manner when updates are applied to the database?

Disc 2: What is the FUNCTION operation? For what is it used? And Present a practical example/ scenario.

NOTE: i need minimum of 300 words for each discussion, total 600 words excluding references, in text citations, in APA format & references are important too.