What is meant by the term division compatibility?

QUESTION: What is meant by the term division compatibility?   [signinlocker] SOLUTION   In order to divide two relations, R and S must be configured such that the set of attributes of S must be a subset of the attributes of R. [/signinlocker]

Why does the relation created as result of a Projection operation on a relation that includes the primary key not contain fewer tuples than those in the source relation?

QUESTION: Why does the relation create a result of a Projection operation on a relation that includes the primary key not contain fewer tuples than those in the source relation?   [signinlocker] SOLUTION   There are no duplicate tuples to eliminate since the value of the attribute(s) that constitute the primary key is unique in…

What is a Cartesian product operation?

QUESTION: What is a Cartesian product operation?   [signinlocker] SOLUTION   The Cartesian product operation is used to combine tuples from any two relations in a combinatorial fashion. [/signinlocker]

What constitutes union compatibility?

QUESTION: What constitutes union compatibility?   [signinlocker] SOLUTION   Two relations R and S are union-compatible if they have the same number of attributes and corresponding attributes in R and S share the same domain. [/signinlocker]