Comparing queries with PHP while loop

Question

Here is my table setup:

• employee: Employee information, name, address, etc...
• group: List of distribution groups.
• employee2group: table that links employees to multiple groups.

I have it setup this way so I can add groups in the future, without having to add columns to my employee table. This may seem like common sense to you all, but I just started with PHP a couple months ago, so everything is still new and confusing to me.

So, I'm working on my update form, which will display a list of check boxes that is populated with a simple SELECT * FROM group query. The idea is to show the ones that an employee is part of as "checked" when I view the employee in the update form.

Currently, my while loop to show the list of check boxes is this:

<?php
 $group_list_query = "SELECT * FROM group"
 $group_list_result = mysql_query($group_list_query, $cmsWrite)
 while ($row = mysql_fetch_assoc($group_list_result)) {
  echo "<input type=\"checkbox\" name=\"distro_{$row['group_name']}\"> {$row['group_name']}";
 }
?>

Pretty simple. I might have some syntax errors in there, but in my code they don't exist, because it works fine.

So what I need to do, is run another query that returns ONLY the names of the groups that the employee belongs to:

SELECT group.group_name 
FROM group JOIN employee2group ON group.group_id = employee2group.group_id 
WHERE employee2group.employee_id ='{$_GET['employee_id']}'

Then, I need to compare the two queries, and output a normal check box when there isn't a match, and output a checked check box when there is a match.

I tried doing a while statement that set $row = query1 and $row2 = query2 , and compare the $row and $row2 values, but then it only returned instances where both queries had results, instead of all of them.

I hope this makes sense, I've been trolling the internet for a while, and haven't found anything that pertains to my problem.

Thanks for reading!

Answer 1

Two solutions :

1 : Get a array of the groupIds that user is a member of, then when looping through the group list. Check if the id is in that array with in_array, if it is dont display the check box

2 : Do a left join on the employee2group table and check if the value = null or not, if its null display the check box.

--

Off question topic but you should also look at using bound paramaters rather than just including them inthe sql statement like that, leaves it open to sql injection otherwise.