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).
mysql_free_result
(PHP 4, PHP 5)
mysql_free_result — 释放结果内存
警告
本扩展自 PHP 5.5.0 起已废弃，并在自 PHP 7.0.0 开始被移除。应使用 MySQLi 或 PDO_MySQL 扩展来替换之。参见 MySQL：选择 API 指南来获取更多信息。用以替代本函数的有：
- mysqli_free_result()
- Assign the value of
nullto the PDO object, or PDOStatement::closeCursor()
说明
mysql_free_result() 将释放所有与结果标识符
result 所关联的内存。
mysql_free_result() 仅需要在考虑到返回很大的结果集时会占用多少内存时调用。在脚本结束后所有关联的内存都会被自动释放。
成功时返回 true， 或者在失败时返回 false。
为向下兼容仍然可以使用 mysql_freeresult()，但反对这样做。
返回值
成功时返回 true， 或者在失败时返回 false。
If a non-resource is used for the result, an
error of level E_WARNING will be emitted. It's worth noting that
mysql_query() only returns a resource
for SELECT, SHOW, EXPLAIN, and DESCRIBE queries.
示例
示例 #1 A mysql_free_result() example
<?php
$result = mysql_query("SELECT id,email FROM people WHERE id = '42'");
if (!$result) {
echo 'Could not run query: ' . mysql_error();
exit;
}
/* Use the result, assuming we're done with it afterwards */
$row = mysql_fetch_assoc($result);
/* Now we free up the result and continue on with our script */
mysql_free_result($result);
echo $row['id'];
echo $row['email'];
?>注释
注意:
为了向下兼容，可以使用下列已废弃的别名： mysql_freeresult()
add a note
User Contributed Notes 3 notes
admin at ifyouwantblood dot de ¶
16 years ago
webmaster at bluesting dot co dot za ¶
13 years ago
mysql_query() also returns a resource for "OPTIMIZE TABLE" statements!
