php - extract icon for each tag from database

Question

I want to display icons for each tag, just like Stackoverflow does.

There are 2 tables related, table_icon and table_event.

table_event is for recording the events happened, of course tags to each event; table_tag is for storing tags and icons to them.

Here's the structure of table_icon:

tag_id
tag_name
icon (an url to an img)

Here's the structure of table_event:

event_id
name
modtime
tag

In table_event, tag is stored "tag1,tag2,tag3" in tag cell.

To make it clearer, Here's an example -

Event: "Kobe Got Hurt", related tags: Kobe, Lakers, Injure

table_event:

event_id ---- 1
name -------- Kobe Bryant got hurt
modtime ----- Mar. 13, 2013
tag --------- Kobe,Lakers,injure

Corresponding table_tag: (say we have those data in table_tag before hand)

tag_id ------ 24
tag_name ---- Kobe
icon -------- .../icon/kobe.png


tag_id ------ 123
tag_name ---- Lakers
icon -------- .../icon/NBA_team_lakers.png


tag_id ------ 36
tag_name ---- injure
icon -------- .../icon/red_cross.png

This is how I extract each tag in PHP:

... // Link to Db and table and call smarty.
$t_sql = mysql_query("SELECT * FROM event WHERE 1");

$id = array();
$name = array();
$tag = array();
$icon = array();

while($t_row = mysql_fetch_array($t_sql)){
    array_push($id, $t_row['event_id']);
    array_push($name, $t_row['name']);
    $tag_array = explode(',', $t_row['tag']);
    array_push($tag, $tag_array);
        // Don't know how to extract icon for each tag.
}

$smarty->assign('tid', $tid);
$smarty->assign('name', $name);
$smarty->assign('tag', $tag);
$smarty->display('event.html');

Any suggestion? Thx in advance!

Answer 1

Use MySQL join with IN clause.

SELECT table_event.*
FROM table_event
WHERE
    EXISTS
    (
        SELECT 1
        FROM table_tag
        WHERE
        table_tag.tag_id IN(table_event.tag)
    )