mysql_field_type
mysql_query() also returns a resource for "OPTIMIZE TABLE" statements!
mysql_free_result
(PHP 4, PHP 5)
mysql_free_result — Libère le résultat de la mémoire
Description
bool mysql_free_result
( resource
$result
)
mysql_free_result() libère toute la mémoire et
les ressources utilisées par la ressource de résultat result.
mysql_free_result() n'est à appeler que si vous avez peur d'utiliser trop de mémoire durant l'exécution de votre script. Toute la mémoire associée à l'identifiant de résultat sera automatiquement libérée.
Liste de paramètres
-
result -
La ressource de résultat qui vient d'être évaluée. Ce résultat vient de l'appel à la fonction mysql_query().
Valeurs de retour
Cette fonction retourne TRUE en cas de
succès ou FALSE si une erreur survient.
Si la valeur passée à l'argument result n'est
pas une ressource, une erreur de niveau E_WARNING
sera émise. Il est important de noter que la fonction
mysql_query() retourne uniquement une
ressource pour les requêtes SELECT,
SHOW, EXPLAIN et DESCRIBE.
Exemples
Exemple #1 Exemple avec mysql_free_result()
<?php
$result = mysql_query("SELECT id,email FROM people WHERE id = '42'");
if (!$result) {
echo 'Impossible d\'exécuter la requête : ' . mysql_error();
exit;
}
/* Utilisation du résultat */
$row = mysql_fetch_assoc($result);
/* Maintenant, nous libérons le résultat et continuons notre script */
mysql_free_result($result);
echo $row['id'];
echo $row['email'];
?>
Notes
Note:
Pour des raisons de compatibilité ascendante, l'alias obsolète suivant peut être utilisé : mysql_freeresult()
Voir aussi
- mysql_query() - Envoie une requête à un serveur MySQL
- is_resource() - Détermine si une variable est une ressource
add a note
User Contributed Notes
mysql_free_result
webmaster at bluesting dot co dot za
16-Mar-2011 04:44
webmaster at wforums dot net
16-Jun-2008 01:02
I agree with Joachim Kruyswijk (posted on 14-Jun-2005 11:42). I just did the test on my beta version of my new site (who needs to get dynamically news and user login from a database) and i use 1000kb less memory when i do not use mysql_free_result. I guess it is because the data it needs to load are not that large (for news: date, short description and for the user login: username, password). It may only be in the user control panel that it will be more, but since that isn't developed totally yet, i'll have to test :p
admin at ifyouwantblood dot de
18-Mar-2008 12:47
yes this function may increase the memory usage if you use unbuffered querys and if you have not fetched all the data from mysql. in this case the mysql api has a problem: you want to free the result but do not want to close the connection. now mysql will only accept another query if all data has been fetched, so the api now must fetch the rest of the data when calling mysql_free_result().
so only use unbuffered querys if you fetch all the data (and need it).
21-Nov-2006 02:53
If you're seeing warnings like "Warning: Unknown: 6 result set(s) not freed. Use mysql_free_result to free result sets which were requested using mysql_query() in Unknown on line 0" and want to turn them off, set mysql.trace_mode = Off in your php.ini
Nairebis
25-Feb-2006 06:00
ALWAYS use this function! I just encountered a bug in my code where I forgot to use this function. I also happen to be using mysql_pconnect() for a persistent connection. If you forget to free the result, it can hold the old result set open indefinitely within the HTTP process.
The upshot (in my application) was that I did updates that happened in a different HTTP process, but they mysteriously didn't show up in another HTTP process. After panicking that MySQL had mysterious data corruption and/or synchronization problems, I traced it back to this where an old result set was held open.
mdeininger at jyujin dot de
20-Sep-2005 04:45
yes, i encountered that too. as far as i could tell, that's because the script is stored in memory after being compiled and that's as much more memory as it needs for a call to that function.
if you always get lotsa data in your results, using this function will decrease memory usage tho, unless you use non-buffered queries (which are preferable unless you absolutely *have* to use mysql_seek(), or you need to do another query while the last one hasn't finished reporting back, as they can provide a small speedup)
macronesia at macronesia dot net
02-Jul-2005 12:11
You not need to use this if you are using PHP 4.
The comment below this comment may explain why it's actually costing more memory.
Joachim Kruyswijk
14-Jun-2005 02:42
Using this function may actually increase the amount of memory used. In my case, the script used 208 bytes less memory when *not* using mysql_free_result().
Check for yourself: call memory_get_usage() at the end of the script.