1-Consider the below database schema:

Professor(ssn, profname, status)

Course(crscode, crsname, credits)

Taught(crscode, semester, ssn)

Query1) Return the ssn of professors who have taught COMP440.

ssn t.crscode ='COMP440' ( Professor * ( crscode t.crscode=c.crscode)

Query2) Return the ssn of professors who have taught COMP440 in Spring 2020 semester.

ssn t.crscode ='COMP440' ( Professor * ( crscode t.crscode=c.crscode)

Query3) Return the ssn of professors who have taught both COMP440 and COMP541.

ssn t.crscode ='COMP440' & COMP541 ( Professor * ( crscode t.crscode=c.crscode)

Query4) Return the codes of courses that have never been taught.

crscode (crscode = Course (Taught))

Query5) Return the names of courses that have never been taught.

crsname (crscode = Course (Taught))

Query6) Return the names of professors who ever taught COMP440.

profname t.crscode = COMP440

ARE THESE CORRECT ??