PHP Australia Conference 2015

mysql_free_result

(PHP 4, PHP 5)

mysql_free_resultLibère le résultat de la mémoire

Avertissement

Cette extension est obsolète depuis PHP 5.5.0, et sera supprimée dans le futur. À la place, les extensions MySQLi ou PDO_MySQL doivent être utilisées. Voir aussi le guide MySQL : choix de l'API ainsi que la FAQ associée pour plus d'information. Voici les alternatives à cette fonction :

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

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User Contributed Notes 7 notes

up
7
webmaster at bluesting dot co dot za
3 years ago
mysql_query() also returns a resource for "OPTIMIZE TABLE" statements!
up
2
Anonymous
7 years ago
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
up
-1
webmaster at wforums dot net
6 years ago
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
up
-2
admin at ifyouwantblood dot de
6 years ago
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).
up
-2
Joachim Kruyswijk
9 years ago
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.
up
-5
macronesia at macronesia dot net
9 years ago
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.
up
-6
mdeininger at jyujin dot de
9 years ago
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)
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