Update selected check box data and remove unchecked data - php

Question

Assume I have users database and base_u_group default will be 0 which are not under any groups.
1)base_users
|base_u_id|base_u_username|base_u_group|
------------------------------------------
| 1 | username 1 | 0 |
| 2 | username 2 | 2, 3, 4 |
| 3 | username 3 | 4 |
| 4 | username 4 | 3,5 |
List down all the users. $checkBox will be automatically checked when belong to that edit group.
echo "<tr>";
echo "<td>". $count .". ".$row_User['base_u_username']. "</td>";
echo "<td align=\"center\"><input type=\"checkbox\" class = \"group\" name=\"userList[]\" value=".$row_User['base_u_id']." ".$checkBox."/></td>";
echo "</tr>";
My problem is how do I insert selected check boxes data without duplication for example: 3, 3, 4, 5 --> 3, 4, 5
and when the check boxes are unchecked, it will delete that group in my base_u_group , for example unchecked the check box for username 2 of group 3
2, 3, 4 --> 2, 4
$gid indicates the selected edit group.
This is what I did so far:
<?php
$userGroup = $_POST['userList'];
foreach($userGroup as $a)
{
$selSQL = base_executeSQL("SELECT * FROM base_users WHERE base_u_id='".$a."'");
while($row_SQL = base_fetch_array($selSQL))
if($row_SQL['base_u_group'] != "0")
{
$data = explode(", ",$row_SQL['base_u_group']);
for($i=0; $i<count($data);$i++)
{
//insert to user group if base_u_group does not find the group ID
if($gid <> $data[$i])
base_executeSQL("UPDATE base_users SET base_u_group='".$gid. ", ". $row_SQL['base_u_group']."' WHERE base_u_id='".$a."'");
}
}
//if the user does not belong to any groups: base_u_group = 0
else
base_executeSQL("UPDATE base_users SET base_u_group='".$gid."' WHERE base_u_id='".$a."'");
}
?>
EDIT: deletion of groups
$data = explode(", ",$row_SQL['base_u_group']);
$ok = true;
for($i=0; $i<count($data);$i++)
{
//insert to user group if base_u_group does not find the group ID
if($gid == $data[$i])
{
$arr = array_merge(array_diff($data,array($gid)));
$newArray = implode(", ",$arr);
base_executeSQL("UPDATE base_users SET base_u_group='".$newArray."' WHERE base_u_id!='".$row_SQL['base_u_id']."' AND base_u_domain='local'");
$ok = false;
}
}
if (ok) base_executeSQL("UPDATE base_users SET base_u_group='".$gid. ", ". $row_SQL['base_u_group']."' WHERE base_u_id='".$a."'");

Answer 1

If you want to stick with your current database design, then your approach is actually the easiest you can do. Moving this logic to MySQL would be very hard, and would have no advantages over your solution. Seems like your approach already handles all the requirements you posted for the adding a group to the user, and deleting the group is pretty much the same logic.
However, I would highly suggest changing your database design. Remove base_u_group column completely, and create a new table user_groups with two columns user_id and group_id. Make a unique key consisting of both of them. Now to add a group, just INSERT into that table, and the unique key will prevent you from inserting the same group twice. Deleting from a group is now also as trivial as deleting from that table. To get all the groups for the user, just execute SELECT group_id FROM user_groups WHERE user_id=$user_id (well, with proper escaping, or via a prepared statement).
You might also make user_id be a foreign key to your current table, so that it disallows inserting invalid user_ids. Also, if you have a table for groups, adding a foreign key from user_groups to that table would help avoid invalid group ids as well.
EDIT: Apparently I misunderstood part of your question. I thought you already have a working solution, and were asking for a better one. I can immediately see an issue in your solution, that causes duplicates, it is easy to fix, just make the following changes to your code:
$data = explode(", ",$row_SQL['base_u_group']);
$ok = true;
for($i=0; $i<count($data);$i++)
{
//insert to user group if base_u_group does not find the group ID
if($gid == $data[$i]) $ok = false;
}
if (ok) base_executeSQL("UPDATE base_users SET base_u_group='".$gid. ", ". $row_SQL['base_u_group']."' WHERE base_u_id='".$a."'");
To see why your code is wrong, think what happens if $data = {1, 2} and $gid is 2 (in which case you obviously don't want to add it). You iterate over every element of $data, so on the first iteration your $data[i] is 1. Since 1 != 2, you update your table and add another 2 at the end
With my changes, I first iterate over all elements of data, and make sure none of them is equal to $gid, and only if that's the case I run a query once to append $gid at the end.
Unfortunately, from your code it is not clear what kind of request you issue for delete, but the logic will be similar. You would go over every element of data, and if any of them is equal to what you want to delete, then just just remove it from data and break from the loop. Then implode your data and store it into the database with an UPDATE query.