Do I've to free mysql result after storing it?

问题:

I was wondering whether or not I've to call the $stmt->free_result() for after I've stored it's result with $stmt->store_result()? Could I rather just call $stmt->close() on the end?

The reason why I'm asking it is because when I call the $stmt->num_rows I've to call the $stmt->store_result() as said here: http://www.php.net/manual/en/mysqli-stmt.num-rows.php, but they don't call the $stmt->free_result() in their example. However, on the $stmt->store_result() they do: http://www.php.net/manual/en/mysqli-stmt.store-result.php.

回答1:

You do not have to expressly free the result, but you can if you'd wish. If you don't, the result will be freed when the statement handle goes out of scope.

回答2:

PHP is pretty lenient with freeing resources. Any resources used by your script, such as SQL connections, will be freed when the script exits. Although it's good programming practice, unless you have many concurrent users there will be very little difference in performance.