Consider the following schema:

Suppliers ( sid: integer, sname: string, address: string )

Parts ( pid: integer, pname: string, color: string )

Catalog ( sid: integer, pid: integer, cost: real )

The Catalog relation lists the prices charged for parts by Suppliers.

Write the following queries in SQL.

1. Find the pnames of parts for which there is some supplier.

2. Find the snames of suppliers who supply every part.

3. Find the snames of suppliers who supply every red part.

4. Find the sids of suppliers who supply only red parts.

5. Find the sids of suppliers who supply a red part and a green part.