Select Code to Download

+-------------+ +------------------+
| Products    | | Supplier_Product |
+-------------+ +------------------+
...
| P1  | Screw | | S1      | P2     |
| P2  | Screw | +------------------+
+-------------+

SELECT parts.pno 
FROM   parts
WHERE  parts.pname = 'Screw'
...
      (SELECT supplier_parts.pno
       FROM   supplier_parts
       WHERE  supplier_parts.sno = 'S1')

SELECT supplier_parts.pno 
FROM   supplier_parts
WHERE  supplier_parts.sno = 'S1'
...
      (SELECT parts.pno
       FROM   parts
       WHERE  parts.pname = 'Screw')

SELECT parts.pno 
FROM   parts, supplier_parts
WHERE  ( supplier_parts.sno = 'S1' AND
         supplier_parts.pno = parts.pno )
   OR  parts.pname = 'Screw'

#!/usr/bin/perl

use strict;
...
    END_SQL
    return @statements;
}

SELECT city 
FROM   cities, customers
WHERE  customers.city_id = cities.city_id
  AND  customers.credit_rating > 700