How can multiple forms be submitted at once in PHP?

When dealing with multiple forms on a single page in PHP, you can use JavaScript to submit all the forms at once by triggering the submit event of each form. This can be achieved by creating a function that loops through all the forms on the page and submits each one.

```php
<script>
function submitAllForms() {
    var forms = document.getElementsByTagName('form');
    for (var i = 0; i < forms.length; i++) {
        forms[i].submit();
    }
}
</script>
```

Then, you can add a button or trigger to call the `submitAllForms()` function to submit all the forms at once.