It is a good quote, although I think it is ironic that Tom then doesn’t actually say why a subquery is better than a join when no columns from the table are needed in the second :)
Hi James, thanks for commenting. Although perhaps not directly related to the quote, he does point out that the two approaches can result in different answers. He also makes a good point about premature optimization – Strive to the clearest, most intention revealing code and let the optimizer (or compiler) figure out how to make it fast.
It is a good quote, although I think it is ironic that Tom then doesn’t actually say why a subquery is better than a join when no columns from the table are needed in the second :)
Hi James, thanks for commenting. Although perhaps not directly related to the quote, he does point out that the two approaches can result in different answers. He also makes a good point about premature optimization – Strive to the clearest, most intention revealing code and let the optimizer (or compiler) figure out how to make it fast.