Re:A Visual Explanation of SQL Joins (2007)
by quizotic on Tuesday May 28, 2013 @05:16AM
(#5779015)
Really? Even if it NEVER produces the right answer? How is it useful then?
A [inner|left|right|outer|cross|natural|whatever] join B NEVER produces a result that is in either A or B. It produces something larger, that wasn't it A or B before.
It's like trying to describe the result of meiosis with a Venn diagram. It's the combinations that matter, and the combinations are not reflected in the Venn diagram.
A [inner|left|right|outer|cross|natural|whatever] join B NEVER produces a result that is in either A or B. It produces something larger, that wasn't it A or B before.
It's like trying to describe the result of meiosis with a Venn diagram. It's the combinations that matter, and the combinations are not reflected in the Venn diagram.