Criando Slugs em PHP

slug.php

function slug($string,$tabela,$coluna){
    
    if(is_string($string)) {
        
        $string = strtolower(trim(utf8_decode($string)));
        $string = str_replace('?','',$string);
        $string = str_replace(':','',$string);
        $string = str_replace('!','',$string);
        $string = str_replace('.','',$string);

        $before = 'ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖØÙÚÛÜÝÞßàáâãäåæçèéêëìíîïðñòóôõöøùúûýýþÿRr';
        $after  = 'aaaaaaaceeeeiiiidnoooooouuuuybsaaaaaaaceeeeiiiidnoooooouuuyybyRr';           
        $string = strtr($string, utf8_decode($before), $after);
                                
        $replace = array(
        	'/[^a-z0-9.-]/'=>'-', 
        	'/-+/' =>'-',
        	'/\-{2,}/'=>''
       	);

    	$string = preg_replace(array_keys($replace), array_values($replace), $string);
    }
    
    $sel = $this->seleciona("SELECT * FROM ".$tabela." WHERE ".$coluna." LIKE '".$string."%'");
    $contar = mysql_num_rows($sel);
    
    if ($contar > 0) {
    	return $string.'-'.$contar;
	}else{
	   	return $string;
	}

}


$sel = $conecta->seleciona("SELECT * FROM user WHERE id='".$id."'");
$ln = mysql_fetch_assoc($sel);
if($nome != $ln['nome']){
	$slug_user = $conecta->slug($nome,'user','slug');
}else{
	$slug_user = $ln['slug'];
}