Exercise #39 page 2

Solution 3.4.2. The same result gives solution which uses self-join:

Console

Execute

SELECT DISTINCT o.ship 
FROM Outcomes AS o, Outcomes AS o2
WHERE (o.result = 'damaged' OR 
       o2.result = 'damaged'
       ) AND 
       o.battle <> o2.battle AND 
       o.ship = o2.ship;

Here is applied the join of Outcomes table with itself provided that ship is the same, but fights are different. Besides, the ship has been damaged in one of fights. As easy to see, there was no check of a battle in which the ship has been damaged for earlier date.

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SQL Problems and solutions

S. I. Moiseenko

Common mistakes in solving SELECT statement exercises

Database «Ships»

Exercise #39 page 2