Pug’s Place

This portion of my discreet structures textbook is discussing how to get a particular row out of a database. WHY MUST THEY MAKE THIS SOUND SO COMPLICATED?

Let R be a relation of degree m and S be a relation of degree n. The join J_p(R,S), where p <= m and p <= n, is a relation of degree m+n-p that consists of all (m+n-p)-tuples (a_1, a_2,…,a_(m-p), c_1, c_2,…c_p, b_1, b_2,… b_(n-p)), where the m-tuple (a_1, a_2,…,a_(m-p), c_1, c_2,…c_p) belongs to R and the n-tuple (c_1, c_2,…c_p, b_1, b_2,… b_(n-p)) belongs to S.

What the hell did that just say!? I’ve been performing complicated database operations and even writing complicated database programs for more than 5 years and I don’t understand that bloody important definition.

At least I know how to do the problems, if not how to read the chapter… arrrrggh….