如何使用html和php安排我的表单

Question

The problem I have is that there is no results in the "category" option. I tried to use two whiles but that doesn't work either.

This is my php:

try{
             $sel=$pdo->prepare("Select * from
                         actors inner join cat
                         on actors.id=cat.id");

    $sel->bindColumn(1,$actors_id);
    $sel->bindColumn(2,$actors);
    $sel->bindColumn(3,$cat_id);
    $sel->bindColumn(4,$cat);
    $sel->execute();




}catch(PDOException $e){

     die("error: " . $e->getMessage());

 }

And This is my html:

<form action="" method="post">

    <label for="author">Author</label>
       <Select id="author">

      //Show data from php file:

    <?php while($sel->fetch()):?>
        <?php echo "<option value='$actors_id'>$actors</option>";?>
    <?php endwhile; ?>
       </Select>

       <label for="category">Category</label>

       <Select id="category">

      //Show data again from php file:

    <?php while($sel->fetch()):?>
        <?php echo "<option value='$cat_id'>$cat</option>";?>
    <?php endwhile; ?>
       </Select>     
    </form>

And this is how it looks like:

As you can see, there is no info display in the "category" option.

If I change the html to something like this, it doesn't work either:

<Select id="author">

    <?php while($sel->fetch()):?>
        <?php echo "<option value='$actors_id'>$actors</option>";?>
       </Select>

       <label for="category">Category</label>
       <Select id="category">

        <?php echo "<option value='$cat_id'>$cat</option>";?>
    <?php endwhile; ?>
       </Select>

Now it looks like this:

Do you have any suggestion?

Answer 1

You need to be cleaner in your return -

<?php 
$result = $sel->fetchAll(PDO::FETCH_OBJ); //return an object
foreach($result as $actor) {
     echo '<option value=' . $actors->actor_id .'>'. $actor->actors .'</option>'; // note the quotes
}

?>

You can loop through the result as many times as you need to, without re-fetching the data.

Answer 2

Your first while loop fetches all rows from the PDOStatement object, so when you call while ($sel->fetch()) a second time, it immediately returns false . If you want to use the results in essentially two separate loops, fetch all rows first into an array of rows, then loop over that array. Do so with fetchAll() instead of binding to variables via bindColumn() .

In fact, I would almost always recommend fetching first rather than during the display logic, except for very large rowsets where the memory consumed by fetching it all at once would be taxing on your system.

// Get all the rows as an array
$rows = $sel->fetchAll(PDO::FETCH_ASOC);

// Later loop for the items you need as many times as you need
// Each new foreach will iterate the entire $rows array from start to end
<?php foreach ($rows as $row): ?>
<?php echo "<option value='{$row['actors_id']}'>" . htmlspecialchars($row['actors']) . "</option>";?>
<?php endforeach; ?>

<?php foreach ($rows as $row): ?>
<?php echo "<option value='{$row['cat_id']}'>" . htmlspecialchars($row['cat']) . "</option>";?>
<?php endforeach; ?>

Don't forget to call htmlspecialchars() on the output, to ensure it is properly encoded for HTML. I haven't done so on cat_id,actors_id on the assumption those are known to be integers, but if not, then you should use htmlspecialchars($row['cat_id'], ENT_QUOTES) to ensure the HTML attributes are correctly quoted.