Do not display if field is empty

( sorry for posting here, but my registration email is yet to be received )

I use his code to display a file download button.
However, I would like to hide the button if there is now file uploaded by admin.

add_action( 'woocommerce_single_product_summary', 'wc_download_limited_offer_detail', 31 );
function wc_download_limited_offer_detail() { 

if ( has_term( 'offers', 'product_cat' ) ) {
echo "<div id='dlbtn'><span class='dlbtn'><a target='_blank' href=";
echo the_field('download_limited_offer_detail');
echo ">DOWNLOAD LIMITED OFFER DETAIL</a></span></div>";

}
}

Thank you
https://wordpress.org/plugins/advanced-custom-fields/