MySQLi Numrows Errors

		$sql_str		=	"SELECT * FROM mydb.mytab WHERE `field` LIKE '%something%';";
		$dbc	 		=	new mysqli(localhost,myusr,mypwd,mydb) or die(mysqli_error());
		$qry_res		=	$dbc->query ( $sql_str );
		$qry_nrs		=	$qry_res->num_rows;