从mysql（php）正确检查复选框

Question

I have a problem with checkboxes. I have some project they you can filter at categories. So the problem is when you want edit a project that automatic the correct category are checked. here you see a project but the categories are empty

In mine databank I use is a combo table - one to insert my categories and one for the project and there I have a combo table from.

Here you see my code for display the checkboxes and select for editing so now I looking for some help, for checked the correctly checkbox that belongs to that project.

<div id="categoriefilter">
  <?php     
  $sql = "SELECT * FROM `categories` ORDER BY `id` ASC";
  $cats = DB::getResult($sql);
  foreach($cats as $cat){
  ?>
  <label>
      <input name="cat[]" type="checkbox" value="<?php echo $cat['id']; ?>" >
      <?php echo $cat['categorienaam']; ?>
  </label>
  <?php
  }
  ?>
</div>

Answer 1

If I understand your question correctly. You need 3 tables here

Table1 : projects id, name, ...
Table2: categories id, name, ...
Table3: projects_categories project_id, category_id, ...

The third table is needed to store the categories which are selected for projects

And inside your project page
You need to do the followings:

1. Select your project by its id
2. Select categories
3. Select categories related to the project ( from Table3 )

---

Here is example ( this is not a working code, just a showcase )

//  your project
$project = DB::getResult("SELECT * FROM project WHERE id = :id "); // <== id here

// list of categories
$categories = DB::getResult("SELECT * FROM categories ");

// list of categories for this project
$project_categories = DB::getResult("SELECT category_id FROM projects_categories WHERE project_id = :project_id ");
$project_categories = (array) $project_categories; // in case DB::getResult is not array

<?php
    foreach($categories as $category) :
?>
<label>
    <input name="cat[]" 
        <?php if(in_array($category['id'], $project_categories)) echo 'checked="checked"'; ?>
        type="checkbox" value="<?= $category['id']; ?>" >
    <?php echo $category['name']; ?>
</label>
<?php endforeach; ?>