How can i exclude some records from an mysql query based on another query

Question

I need to exclude some records from a table, and show them, then, i need to show the other records, which were excluded.

I got 3 tables:

+----Songs----+   +----Tags----+   +----s_in_tag----+
|     id      |   |     id     |   |       id       |
|    title    |   |    name    |   |     song_id    |
+-------------+   +------------+   |      tag_id    |
                                   +----------------+

In table Songs I store a list of songs, table Tags have a list of tags, and table s_in_tag bind those 2 tables.

Let say i have in Songs : 1, song nr1. In Tags : 1, POP; 2, Rap; 3, Classical. And in s_in_tag : 1, 3, 2. This means that song nr1 has tag Classical

I want to be able to add/remove tags in my dashboard, but how do i make a right query which will get all song tags, and will show them as a checked checkbox, and then other tags from table Tags as unchecked checkboxes?

I've got this so far:

SELECT * FROM tags
JOIN s_in_tag
ON tags.id = s_in_tag.tag_id
WHERE s_in_tag.song_id = *song id*
AND s_in_tag.tag_id NOT IN (SELECT tags.id FROM tags) GROUP BY tags.id

Im just trying what I found on internet, hope someone can help me there.

Answer 1

Why don't you include them both in the same query?

SELECT t.id, t.name, st.id IS NOT NULL AS is_checked
  FROM Tags t
  LEFT JOIN s_in_tag st ON t.id = st.tag_id AND st.song_id = [song_id];

Answer 2

Try this:

<?php
// Query 
$sql = "SELECT t.id, t.`name` AS tag, IF(st.`id`, 'checked', 'unchecked') AS checkstatus
FROM tags t
LEFT JOIN s_in_tag st ON st.`tag_id` = t.`id`";

$rs = mysql_query($sql);
while ($row = mysql_fetch_assoc($rs)) { 
$checked = $row['checkstatus'] ? ' checked="checked" ' : '';
?>
<p><input type="checkbox" <?php print $checked; ?> /> <?php print $row['tag']; ?> </p>  
<?php } ?>

Answer 3

I would create two sql queries. One that gets you all tags and the other that gets you all used tags.

$allTags = "SELECT * FROM tags";
$usedTags = "SELECT * FROM s_in_tag;

On php layer you iterate through the $allTags array and on every iteration you look in the $usedTags array and if it contains the current tag you mark it as checked.

foreach($allTags as $key=>$value)
{
    if (in_array($value, $usedTags))
    {
        echo "<input type='checkbox' checked /> ".$value;
    }
    else
    {
        echo "<input type='checkbox' /> ".$value;
    }
}

The php part is not tested but should work.