如何处理从联合选择语句接收的数据

Question

Hello I'm trying to create a search function for my website. I have this method that has the query

public function search_all($data)
{
    $query = [];

    $result = $this->db->query('
        SELECT blog_title FROM blog WHERE blog_title LIKE "%'. $data . '%" 
        UNION
        SELECT body FROM blog WHERE body LIKE "%'. $data . '%" 
        UNION 
        SELECT username FROM users WHERE username LIKE "%'. $data . '%"
    ');

    while ($row = $result->fetch_assoc()) 
    {
        $query[] = $row;
    }

    $result->free();

    return $query;

    $mysqli->close();
}

Then I have the method that handles the user input

public function search()
{
    if (isset($_POST['search']))
    {
        $search_term = trim($_POST['search_term']);

        $terms = $this->search->search_all($search_term);

        foreach ($terms as $term) 
        {
            var_dump($term);
        }
    }
}

The search works sort of. If I search a username or a blog title it then I can echo it back like this

echo $term['blog_title'];

if I var_dump then I get something like

array (size=1)
    'blog_title' => string 'BillyBob' (length=8)

My question is why does it always retrun blog_title as the key. I thought I would have to do something like

If I want to echo the blog title

echo $term['blog_title'];

If I want to echo the username

echo $term['username'];

Answer 1

In the union of two tables either the fields of both tables should be same or the alias should be same for both the tables.

Please try this query.

$result = $this->db->query('
    SELECT body,blog_title,'' as username FROM blog WHERE blog_title LIKE "%'. $data . '%" OR body  LIKE "%'. $data . '%"  OR username  LIKE "%'. $data . '%"
    UNION 
    SELECT '' as body,'' as blog_title,username FROM users WHERE username LIKE "%'. $data . '%"
');

This query will select records when search will match with blog_title or body or username. And you will able to fetch all three fields' value for fetched records.