如果php echo内容为空，则隐藏div

<div class="botontour"><a href="<?php echo $currentItem['video'];?
>">Video Tour 3D</a></div>

I want to hide the entire "botontour" div if the php echo has no return.

in this case you can check if it's empty :

<?php
if (!empty($currentItem['video'])) {
?>
    <div class="botontour"><a href="<?= $currentItem['video'];?>">Video Tour 3D</a></div>
<?php
}
?>

<?php 
    if(isset($currentItem['video']) && !empty($currentItem['video'])){
    ?>

 <div class="botontour"><a href="<?= $currentItem['video'];?>">Video Tour 3D</a></div>

<?php  } >

empty — Determine whether a variable is empty

<?php

if(!empty($currentItem['video'])) { ?>

<div class="botontour"><a href="<?php echo $currentItem['video'];
>">Video Tour 3D</a></div>

<?php } ?>

You can use strlen() : http://php.net/manual/fr/function.strlen.php

    <?php if(strlen($currentItem['video']) != 0) { ?>
    <div class="botontour"><a href="<?php echo $currentItem['video'];?
     >">Video Tour 3D</a></div>
    <?php } ?>

Or Empty() : http://php.net/manual/fr/function.empty.php

    <?php if(!empty($currentItem['video'])) { ?>
    <div class="botontour"><a href="<?php echo $currentItem['video'];?
     >">Video Tour 3D</a></div>
    <?php } ?>