如何在PHP中创建哈希列表?
如何在PHP中创建标签列表 我有一张“posts”表 此表包含3个字段(id、文本、哈希) 像这样的数据如何在PHP中创建哈希列表?,php,mysql,Php,Mysql,如何在PHP中创建标签列表 我有一张“posts”表 此表包含3个字段(id、文本、哈希) 像这样的数据 id => 1 text => i'm from #us hash => ,us id => 2 text => i #love #us hash => ,love ,us id => 3 text => i will travel to #us cus i #love it hash => ,us ,love id
id => 1
text => i'm from #us
hash => ,us
id => 2
text => i #love #us
hash => ,love ,us
id => 3
text => i will travel to #us cus i #love it
hash => ,us ,love
id => 4
text => i will go to #us #now
hash => ,us ,now
我想展示这样的数据
顶端散列
us
love
now
您的代码中有什么不起作用?您不需要这样的设置。您应该有这样的设置:posts(id,text)
,标记(id,tag)
,以及关系(id,post\u id,tag\u id)
。然后,您可以按tag\u id DESC
对关系表进行排序,并提取最常用的前3个。如果tags
表只存储不必要的代理主键,而不存储任何信息,那么就没有理由使用它。relationships
表也不需要id
列post_id,tag
本身就是主键。似乎你已经养成了一个习惯,在每个表中添加一个id
列,即使它不需要。是的,你是对的。但是,如果程序员打算最终存储更多的数据而不仅仅是一个标记名,那么使用表可能是有意义的,例如,如果他/她将标记与其他信息相关联。您还可以在标记
表中有一个名为计数
的列,该列会定期更新(或者每当添加/更新帖子时,其频率可能低于访问顶部散列),这可能会加快查询速度?不确定。我试过了
`
<?php
$sql = new MySQLi('localhost', 'root', '', 'database');
// A MySQLi connection
/* Database setup:
`posts`
`id`
`text`
`tags`
`tag`
`post_id`
*/
function add_post ($text, $tags = array ()) {
global $sql;
$sql->query('INSERT INTO `posts` (`text`) VALUES ("'.$sql->real_escape_string($text).'");');
// Insert the post into the posts table
$postID = $sql->insert_id;
// Capture its id
if (count($tags) != 0) {
foreach ($tags as &$tag) {
$tag = $sql->real_escape_string($tag);
}
unset($tag);
// Escape every tag
$sql->query('INSERT INTO `tags` (`tag`, `post_id`) VALUES ("'.implode('", '.$postID.'), ("', $tags).'", '.$postID.');');
// Insert the tags associated with this post as records in the tags table
}
}
// If/when you write update_post and delete_post functions, you will need to manage the tags associated with them as well
// Probably it's best to use a relational system like InnoDB
function get_top_tags ($num = 3) {
global $sql;
$result = $sql->query('SELECT `tag`, COUNT(`tag`) AS `frequency` FROM `tags` GROUP BY `tag` ORDER BY `frequency` DESC LIMIT '.(int) $num.';');
// Get the tags in order of most to least frequent, limited to $num
$tags = array ();
while ($row = $result->fetch_assoc()) {
$tags[] = $row['tag'];
}
// Turn them into an array
return $tags;
}
// Example usage:
add_post('This is a new post.', array ('this', 'post', 'new'));
add_post('This is an old post.', array ('this', 'post'));
add_post('That is a medium-aged post.', array ('post'));
?>
<h1>Top Tags</h1>
<ol>
<?php
foreach (get_top_tags(3) as $tag) {
?>
<li><?php echo $tag; ?></li>
<?php
}
?>
</ol>
<!-- Should print
1. post
2. this
3. new
-->