mysql - Checking entry in a table with PHP PDO issue -

i test whether entry of particular uid , mid exists in table user_saved, here's did

$result = $db->prepare("select * user_saved uid = ? , mid = ?");              $result->execute(array($_session['uid'], $itemid['mid2']));           $test = $result->fetch(pdo::fetch_assoc);                  if (isset($test)){         exist       } else {                     doesn't exist               } 

the issue tried uid , mid doesn't exist, goes isset if statement, why this? what's better way this?

isset checking whether variable exists or not use strlen function or array count function

<?php $bbnq = sprintf("select login users id = %u",27); try     { $req = $db_bbn->query($bbnq); } catch (exception $e)     { bbnf_pdo_error($e,__file__,__line__); } if ( $r = $req->fetch() )     { echo "this query has row result"; } else     { echo "this query has empty result"; } ?>