打印所有类别的帖子及其类别名称

Question

I try to achieve the following:

• Some great post title (posted in Sport)
• Another title of a post here (posted in Space)
• Cool title of some post (posted in Technologies)
• And so on...

I display all posts from all categories and put the category name next to each post. I do not understand where and why fail. All posts are multiplied by the number of categories. Here is what I have till now:

posts table:

post_id
post_title
post_content
category_id



categories table:

category_id
category_name
category_description

And my queries and PHP code:

// I select all categories with their id and name
$stmt = $db->prepare("SELECT * FROM categories");
$stmt->execute();
$row_categories = $stmt->fetchAll(PDO::FETCH_ASSOC);

// I select all posts too
$stmt = $db->prepare("SELECT * FROM posts");
$stmt->execute();
$row_posts_all = $stmt->fetchAll(PDO::FETCH_ASSOC);

And then:

foreach ($row_posts_all as $array_index_number => $name_of_index) {

    foreach ($row_categories as $array_index_number_categories => $name_of_index_category) {

        print $name_of_index['post_title'] . " posted in: " . $name_of_index_category['category_name'] . "<br><br>";
    }
}

I think this two foreaches part do things wrong. I can do one foreach to display all the posts but I do not know how to get their category names and put them next.

Answer 1

That's the reason we have JOINS ,

SELECT * from posts p
LEFT JOIN categories c on c.id = p.category_id

And then you can simply need a single loop,

foreach ($row_posts_all as $array_index_number => $name_of_index) {
    echo $name_of_index['post_title'] . " posted in: " . $name_of_index['category_name'] . "<br><br>";
}

Answer 2

select P.*, C.* from posts P
inner join categories C on C.category_id = P.category_id

You don't need 2 sql requests. So you don't need 2 loops