A modern guide to SQL JOINs

Author: Alexey Makhotkin squadette@gmail.com , (~8800 words) &#xA; There are many SQL JOINs guides and tutorials, but this one takes a&#xA;very different approach. Specifically: &#xA; &#xA; &#xA; LEFT JOIN is presented first, INNER JOIN second; &#xA; &#xA; &#xA; strict discipline of using ID equality comparison in ON condition; &#xA; &#xA; &#xA; we distinguish between N:1, 1:N and M:N cases of…