How to echo 'checked' if checkbox is checked

Question

In the "edit view" of my form I have a list of checkboxes and I want to check the ones which are in the table book_have_languages (notice that one book can have more than one language).

Code:

<?php $query_c = mysqli_query($mysqli, "SELECT id_language, name_language FROM languages ORDER BY name_language;")
                                                        or die('error '.mysqli_error($mysqli));
while ($data_c = mysqli_fetch_assoc($query_c)) {
      echo "<div class='checkbox'><label><input type='checkbox' name='languages[]' value='$data_c[id_languages]'>$data_c[name_language]</label></div>";

      $sql = "SELECT id_book, id_language FROM book_have_languages WHERE id_book=3";
      $res = $mysqli->query($sql) or die("error: ".$sql);
      $results = array();
      while($row = mysqli_fetch_assoc($res)) {
         $results[] = $row;
      }
      foreach ($results as $result){
       if($result['id_language'] == $data_c['id_language']){
        echo"<div class='checkbox'><label><input type='checkbox' name='languages[]' value='$data_c[id_language]'checked >$data_c[name_language]</label></div>";
       }

      }


}
?>

Result:

If my table is:

id_book | id_language

3 - 2

3 - 5

3 - 6

Languages 2, 5, 6 are checked but they appear duplicated. How can I indicate in the first echo only show the languages that there aren't in the table?

Answer 1

You are looping through the languages, but not through the languages a book has. If your table is as described, $data_idi should have more than one result, and you're only matching the first one. You should loop within those results also.