Question

I’m having a little trouble with a mysql_fetch_assoc script i hope you can help with.

Background:
I’m retrieving my data for part of my site with a typical MySQL query and echoing out the results from various fields etc etc from my main table whose structure is not important but which has a unique id which is ‘job_id’

In order to have multiple catagories associated with that ‘job_id’ i have employed a toxi solution which associates catgories to each ‘job_id’.

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
)

When i echo out the info from the main table (using ‘job_id’) i also want to echo all the catagories which that job_id is matched against, which id using:

$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);

In my code i’m using this to echo out the matched catagories:

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

I have two problems:

1. The above echo seems to be ignoring the first tag name all together, so if a job is tagged with six catagories, it only echos five. If a job is only tagged with one, I get nothing. The query works in the SQL shell, so I’m assuming the problem lie in the PHP.
2. When I do get multiple echos, I want to be able to seperate them with a comma or a |, but I’m unfamiliar with using group_concat in queries, so I could also use a little help there.

Answer 1

Because mysql_fetch_assoc is already called once before the while loop, the first row is always discarded.

This should solve your problems:

$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>