This advanced SQL exercise is part of the book: Advanced SQL – Practical Techniques and Use-Cases, which includes 100 day-to-day SQL challenges (and solutions), need-to-know advanced features, and key concepts.
An electronics store has a table that contains various products (3 in total):
CREATE TABLE Gadgets (gid int identity(1,1) primary key, gdesc varchar(25)) GO
Given an additional table that specifies customers, and the various products they own:
CREATE TABLE users (userID int identity(1,1), username varchar(25), gdesc varchar(50)) GO