<?  $sql = "SELECT * FROM calls_engineers WHERE call_ce = '$diary_id'";
      $result = mysql_query($sql) or die(mysql_error());
      $row2 = mysql_fetch_array($result);
      $sql = "SELECT * FROM users WHERE type = 'engineer' ORDER BY first_name";
      $result = mysql_query($sql) or die(mysql_error());
      while ($row = mysql_fetch_array($result)){ ?>
          <div style="width:70px; float:left">
              <?
                  if($row2['engineer_ce'] == $row['id']){
              ?>
              <input type="checkbox" name="engineer[]" checked="checked" value="<? echo $row['id']; ?>" />
              <? echo '   '.$row['first_name'];
              } else { ?>
                  <input type="checkbox" name="engineer[]" value="<? echo $row['id']; ?>" />
              <? echo '   '.$row['first_name'];
              }?>
          </div>
  <?
      }

  ?>

$row2 = mysql_fetch_array($result);

<?

  $sql = "SELECT * FROM users WHERE type = 'engineer' ORDER BY first_name";
  $result = mysql_query($sql) or die(mysql_error());
  while ($row = mysql_fetch_array($result)){ ?>

      <div style="width:70px; float:left">
          <input type="checkbox" name="engineer[]" <?
              $result2 = mysql_query("SELECT * FROM calls_engineers WHERE call_ce = '".mysql_real_escape_string($diary_id)."' AND engineer_ce = ".$row['id']);
              if(mysql_num_rows($result2) > 0) echo 'checked="checked"';
             ?> value="<? echo $row['id']; ?>" />
          <? echo '   '.$row['first_name']; ?>
      </div>

  <? } ?>