我在计数行并将其在php中排序时遇到问题

Question

I have a table called "tags" which stores all given tags to an image row by row:

I want to get data about the "most popular" tags, so I tried counting them. I manage to successfully list and count the tags image but I can not manage to sort() them by value.

I have tried using ar/sort(), creating a third loop....

<?php

function count_tags_sql($tag) {

  global $db;

  // count
  $sql = $db->query("SELECT tags FROM tags WHERE tags = '$tag'");
  $sql->execute();

  echo $tag.'('.$sql->rowcount().')<br>';


}

// get tags

$sql = $db ->prepare("SELECT * FROM tags");
$sql->execute();

$rows = $sql->fetchAll(PDO::FETCH_ASSOC);

  foreach($rows as $row){

    $tagname[] = $row['tags'];

  }

// remove duplicates
$tagname = array_unique($tagname);

// output tags
foreach($tagname as $tag) {

  echo count_tags_sql($tag);

}

?>

Answer 1

您想使用计数，最好是这样：

SELECT tags,count(*) as usages FROM tags GROUP BY 1 ORDER BY 2 DESC;

Answer 2

change your count_tags_sql function and $tagname for loop to below

function count_tags_sql($tag) {
  global $db;
  // count
  $sql = $db->query("SELECT tags FROM tags WHERE tags = '$tag'");
  $sql->execute();
  return $sql->rowcount()
}
// output tags
$tag_arr = [];
foreach($tagname as $tag) {
    $tag_arr[$tag] = count_tags_sql($tag);
}
// Sorted array
asort($tag_arr);