Typical mistakes at the solution of SELECT statement exercises

Then followed a number of exemplary dialogues between the teacher and the student, altogether incomprehensible for the rational ear and absurd in terms of any dualistic or binary logics; teachers mostly answered their students’ questions by beating them on the head with a stick, pouring out a jug of cold water over their head, toeing them out of the room or at best repeating the same question staring into their face.

Hopscotch, Julio Cortazar

In this Part fallacious solutions of the problems of instructional level and of the first rating tests are analyzed on the site «SQL Exercises». Our method is not to provide «correct» solutions apart from the simplest problems, but to facilitate the process of studying for the beginners at the introductory level. Nevertheless, many solutions quoted here are almost correct, and their correction won’t pose any difficulty, if one identifies the cause of the mistake. Some clues are provided in the special Chapter «Tips and solutions», in which additional comments are given, and some alternative approaches to solution of the problem are considered.

Content:

(Chapter 1) Database "Computer firm"
(Chapter 2) Database «Recycled materials company»
(Chapter 3) Database «Ships»
(Chapter 4) Tips and solutions