Deactivate link if URL column value is empty

function createLink($type, $link, $data, $customLink=""){
		//echo( "type:".$type." link:". $link." label:". $data." custom link:". $customLink."<br>");
		$output="";

                if($link=="") return $data;
                      
		switch($type){
			case '0':{
				$output = $data;
			}break;
			case '1':{
				$output = '<a target="_blank" href="'.$link.'">'.$data.'</a>';
			}break;
			case '2':{
				$output = '<a target="_blank" href="?option=com_content&view=article&id='.$link.'">'.$data.'</a>';
			}break;
			case '3':{
				$link = str_replace('@ID', $link, $customLink);
				$output = '<a target="_blank" href="'.$link.'">'.$data.'</a>';
			}break;
			default:{
				$output = $data;
			}
		}
		return $output;
	}