Question

Which of the following queries contains a non-equality join?
a. SELECT title, authorid
FROM books, bookauthor
WHERE books.isbn = bookauthor.isbn
AND retail > 20;

b. SELECT title, name
FROM books JOIN publisher
USING (pubid);
c. SELECT title, gift
FROM books, promotion
WHERE retail >= minretail
AND retail <= maxretail;
d. none of the above

Answer 1

c. SELECT title, gift
FROM books, promotion
WHERE retail >= minretail
AND retail <= maxretail;

Explanation:

Non Equi Joins is a joins which contains an operator other than ‘=’ in the join condition

in A option  contains = in where clause and B options contains join, so both are omitted as non-equi joins.