PHP mysql search multiple tables using a keyword

I have three tables in my database which are:

messages
topics
comments

Each of these tables has two fields called 'content' and 'title'. I want to be able to use 'Like' in my sql statement to look at 'messages.content', 'messages.title', 'topics.content', 'topics.title', 'comments.content' and 'comments.title' using a keyword.

So far, my query is able to find results from only one table:

mysql_query("SELECT * FROM messages 
WHERE content LIKE '%" . $keyword . "%' 
OR title LIKE '%" . $keyword ."%'");

I am also wondering, once I get the results from multiple tables, how can I tell what result is from what table?

Any help would be greatly a开发者_高级运维ppreciated!

---

$query = "(SELECT content, title, 'msg' as type FROM messages WHERE content LIKE '%" . 
           $keyword . "%' OR title LIKE '%" . $keyword ."%') 
           UNION
           (SELECT content, title, 'topic' as type FROM topics WHERE content LIKE '%" . 
           $keyword . "%' OR title LIKE '%" . $keyword ."%') 
           UNION
           (SELECT content, title, 'comment' as type FROM comments WHERE content LIKE '%" . 
           $keyword . "%' OR title LIKE '%" . $keyword ."%')";

mysql_query($query);

So, you are getting result from all of the three tables, and you can identify which row came from which table by looking at its type value.

---

What you are probably looking for is the UNION command:

SELECT id, 'messages' as 'table' FROM messages 
  WHERE content LIKE '%keyword%' 
    OR title LIKE '%keyword%'
UNION
SELECT id, 'topics' as 'table' FROM topics
  WHERE content LIKE '%keyword%' 
    OR title LIKE '%keyword%'
UNION
SELECT id, 'comments' as 'table' FROM comments
  WHERE content LIKE '%keyword%' 
    OR title LIKE '%keyword%'

---

Two search in other tables you use:

SELECT `categories`.`title`, `posts`.`title` WHERE `categories`.`title` LIKE {$a} OR `posts`.`title` LIKE {$a}

The CATEGORIES and POSTS are tables of your database.

---

Html Search form:

<div class="header_top_right">
    <form action="search.php" method="GET" class="search_form">
        <input type="text" placeholder="Text to Search.." name="search">
        <input type="submit" class="btn btn-default" value="">
    </form>
</div>

Search.php:

<?php
    if (isset($_GET['search']) || !empty($_GET['search'])) {
        $search = mysqli_real_escape_string($db->link, $fm->validation($_GET['search']));
    }
    else{
        header("Location:404.php");
    }
?>
<?php
    $query = "SELECT * FROM news_post WHERE title LIKE '%$search%' OR body LIKE '%$search%' OR tags LIKE '%search%'";
    $post = $db->select($query);
    if ($post) {
        while ($result = $post->fetch_assoc()) {
            echo"Database data like, $result['title']";
        }
    }
    else{
        echo "result Not found";
    }

include database.php in search.php

class Database{
    public function select($query){
        $result = $this->link->query($query) or die($this->link->error.__LINE__);
        if($result->num_rows > 0){
            return $result;
        }
        else {
            return false;
        }
    }
}
$db = new Database();