Can the following be done entirely with PHP and not using Javascript...

There is a form that has a required field.

When the user clicks the "Submit" button...

1.) If the required field was left blank, then the form should re-appear with a warning message next to the omitted field stating, ERROR: Field must contain a value.

2.) If the form was filled out correctly, then the form should re-direct to another page (which is the next step in whatever process).

If so, what would the PHP code look like?