TABLE `tags` (
`tag_id` INT NOT NULL AUTO_INCREMENT,
`tag_name` VARCHAR(20) NOT NULL,
PRIMARY KEY (`tag_id`)
)

CREATE TABLE `tag_relational` (
`job_id` INT NOT NULL,
`tag_id` INT NOT NULL
)

$query = "SELECT * FROM tags t
JOIN tag_relational r
ON t.tag_id=r.tag_id
WHERE r.job_id = $job_id";

$result=mysql_query($query) or die(mysql_error());
$cats=mysql_fetch_assoc($result);

<p>Job Catagories | <?php while ($cats=mysql_fetch_assoc($result)) { echo $cats['tag_name'];}?></p>

$query = "SELECT * FROM tags t
JOIN tag_relational r
ON t.tag_id=r.tag_id
WHERE r.job_id = $job_id";

$result=mysql_query($query) or die(mysql_error());

<p>Job Catagories |
<?php
$first = true;
while ($cats=mysql_fetch_assoc($result)) {
    if($first){
        $first = false;
    } else{
        echo ", ";
    }
    echo $cats['tag_name'];
}
?>
</p>