PHP 缓存 sql 结果

Question

我有一些从数据库获取数据的mysql查询，结果在24小时内不会改变，我想存储在缓存中，如何缓存24小时结果并在过期后重新缓存它们？

<?php
$getTopics=$db->loadAssoc($db->setQuery("SELECT * ,  categories.title AS category_title, 
                                        status_topics.title as status_topic
                                        FROM contents
                                        JOIN categories ON categories.id = contents.category
                                        JOIN status_topics ON status_topics.id = contents.status "));

$getCategories           = $db->loadAssoc($db->setQuery("SELECT * FROM categories"));
$getTags                 = $db->loadAssoc($db->setQuery("SELECT * FROM status_topics"));
$getPages                = $db->loadAssoc($db->setQuery("SELECT * FROM pages"));
$getSiteInformation      = $db->loadRow($db->setQuery("SELECT * FROM settings JOIN categories"));
$getSubDomainInformation = $db->loadAssoc($db->setQuery("SELECT * FROM sub_domains"));
$getUserInformation      = $db->loadAssoc($db->setQuery("SELECT * FROM users"));
?>

Answer 1

一个非常简单的、无数据库的缓存机制：

$filename = 'cache.txt';
if (filemtime($filename) < time()-24*3600) { //older than a day
  /*get your data*/
  file_put_contents($filename, serialize(array($getCategories, $getTags, [...])); //your data in a serialized form
} else {
  $data = unserialize(file_get_contents($filename));
  list($getCategories, $getTags, [...]) = $data;
}

（显然你应该用保存数据的变量替换 [...]）