SQL

Consider a relational database containing the following schemas (see figure: Catalogue, Suppliers, Parts). The primary key of each table is indicated by underlining the constituent fields.

SELECT s.sno, s.sname
FROM   Suppliers s, Catalogue c
WHERE  s.sno = c.sno AND
       cost > (SELECT AVG (cost)
               FROM Catalogue
               WHERE pno = 'P4'
               GROUP BY pno);

The number of rows returned by the above SQL query is