PHP While循环可搜索多个MySQL查询

Question

I am trying to loop through a searched tag and gather all posts related to that tag. For that I know I will need to either use the while or foreach loop.

The variable is gathered by: $tag = trim($_GET['tag']);

Then, I am going to search through the tags table like so:

  $stmt = $mysqli->prepare('SELECT post_id FROM tags WHERE tag = ?');
  $stmt->bind_param('s', $tag);
  $stmt->execute();
  $stmt->bind_result($post_id);
  $stmt->store_result();
  $rows = $stmt->num_rows;
  $stmt->fetch();
  $stmt->close();

This will likely return multiple rows as it is searching through all the posts that have a tag, for example 'trips'.

Then, after gathering the post_id of the relevant tagged posts, I search the posts table to get all the information about the post before outputting it to the user:

  $stmt = $mysqli->prepare('SELECT title FROM posts WHERE id = ?');
  $stmt->bind_param('i', $post_id);
  $stmt->execute();
  $stmt->bind_result($title);
  $stmt->store_result();
  $rows_posts = $stmt->num_rows;
  $stmt->fetch();
  $stmt->close();

My problem is this only will work for one post and I am not sure how to loop this search through so multiple posts with the same tag are returned.

Answer 1

You could join the posts table in the first query.

SELECT posts.title FROM tags
JOIN posts ON posts.id = tags.post_id
WHERE tag = ?

You can use: foreach($stmt->get_result() as $row) {} then.

Answer 2

please learn how mysql join works http://dev.mysql.com/doc/refman/5.0/en/join.html In your example the right query would be:

SELECT posts.title FROM tags join posts on posts.id = tags.post_id where tag = ?

you dont need to connect the data in php anymore then.

Answer 3

Why not using

SELECT title FROM posts P INNER JOIN tags T ON P.id = T.post_id WHERE tag = ?

This will result al titles for the specified tag