RaghuramKrishnan

Question

relation

parts(pid, pname, color)

catalog(sid, pid, cost)

find the sids of suppliers who supply every red part.
can someone give the TRC and DRC expression for this?

Answer 1

For TRC -

{c.sid | catalog(c) AND (∃p)(parts(p) AND c.pid = p.pid AND p.color = "red")}

For DRC -

we will give each attribute a name parts(a,b,c) and catalog(d,e,f)

{d | (∃a)(∃e)(∃c)(catalog(def) AND parts(abc) AND e=a AND c="red")}