53
Disambiguating Attributes
•Sometimes two relations have the same attr:
Person(pname, address, worksfor)
Company(cname, address)
Person(pname, address, worksfor)
Company(cname, address)
SELECT DISTINCT pname, address
FROM Person, Company
WHERE worksfor = cname
FROM Person, Company
WHERE worksfor = cname
SELECT DISTINCT Person.pname,
Company.address
FROM Person, Company
WHERE Person.worksfor = Company.cname
FROM Person, Company
WHERE Person.worksfor = Company.cname
Which
address ?
address ?
