This is from Murach's MySQL 2nd Edititon (pages 146-147)

Write a SELECT statement that returns three columns: vendor_id vendor_name contact_name The vendor_id column from the Vendors table The vendor_name column from the Vendors table Aconcatenation of the vendor_contact_first_name and vendor_contact_last_name columns with a space between Return one row for each vendor whose contact has the same last name as another vendor's contact. This should return 2 rows. Hint: Use a self-join to check that the vendor- id columns aren't equal but the vendor_contact_last_name columns are equal. Sort the result set by vendor_contact_last_name