I've got two tables in my database, one containing groups and one containing users. The users can be a member of those groups even multiple times.
So users contains "id", "name", "lastname", "group", and some others which are not important atm. The table groups contain just an id and a group name. Those groups are dynamic, sometimes a group gets added, and sometimes a group gets deleted.
On the front end, people can add themselves to a group using a form with a select multiple
But I do not get any further than this. I'm facing two issues. data collected from an are in an array, so putting them in a SQL query isn't plain simple. (i was thinking to put al the info from the array into just one variable separated by ",") on the other hand, maybe this table format isn't the best way to do so.
So what I'm I asking from you guys. Is it better to change the table structure and into what? How do I combine an array into one variable so I can put them in the database (separated by ",")<\s>
EDIT!: As recommended by Andy Hall, I 'v created a new table. werkgroep_user with id, werkgroep_id, and user_id.
this is what my select looks like
<select id="testwerkgroep" name="testwerkgroep[]" multiple>
<option value="">geen werkgroep</option>
<option value="1">werkgroep 1</option>
<option value="2">werkgroep 2</option>
</select>
Now I'm facing the problem of getting data from the DB. I want for example all users(name) and their groups(name)
Looks like your Users and Groups tables have a many-to-many relationship. "Many users can be part of many groups".
Without resolving the many-to-many relationship with an intermediary table, you can certainly use a string of comma separated values in the users.group field. You would achieve that by using the implode() function on your array of group IDs:
$commaSeparatedGroupIdString = implode($groupIdArray);
And when you retrieve from the database, you can explode them back out to an array:
$groupIdArray = explode($commaSeparatedGroupIdString, ",");
The second (and, I would say better) method is to resolve the many-to-many relationship with an intermediary table. This table could be named something like group_assignments. One user may have many group_assignments, and one group may have many group_assignments.
The structure of the group_assignment table would be:
id primary key
user_id foreign key to the users.id field
group_id foreign key to the groups.id field
Whenever a user wishes to assign themselves to a group, they would make a submission, and your application would create a new record in the group_assignments table with the ID of the user and ID of the group they submitted to assign themselves to. Retrieving group assignment information for a user would then require the use of a JOIN in your SQL to grab all the associated group_assignment records to your user. Removing an assignment is as simple as removing the appropriate record in the group_assignments table.