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I had a chance to learn a little more about this in another topic:
Both can get basically the same result, but it depends on RDBMS. It seems that the former (implicit) way is old syntax. Now the explicit way (with JOIN clause) seems to be recommended for several reasons, such as code readability.
Yes, you are correct they are the same. It’s great you found more info on the topic. I think it’s debatable on whether EXPLICIT joins are more readable . I personally find implicit joins more concise and readable but don’t have issues working with either methods. It’s best to follow the development standards established by the environment you are working with.
In the exercise 6/7 in this chapter, I tried to use an implicit join (like this)
SELECT book.title as book, chapter.title as chapters
FROM book, chapter
ON book.isbn = chapter.book_isbn;
but the solution marked that only an explicit join would work (like this)
SELECT book.title as book, chapter.title as chapters
FROM book
JOIN chapter
ON book.isbn = chapter.book_isbn;
Why? Wouldn’t both options work, according to the theory? Is this a bug in the solution checker?
I believe both should work, but only the second option was allowed to be correct.