SELECT places.id, COUNT(features.name) as 'count_features' 
FROM places
JOIN features ON places.id = features.place_id
WHERE features.name in ('wi-fi', 'river')
GROUP BY places.id
HAVING count_features = 2

allDiv=2;
function showDv(n){
    for(i=1;allDiv+1>i;i++){
    document.getElementById('d'+i).style.display = 'none';
    document.getElementById('d'+i).parentNode.style.border = 'none'
    }
    document.getElementById('d'+n).style.display = 'block';
    document.getElementById('d'+n).parentNode.style.border = '1px solid black'
  event.preventDefault();
  }