how to create queries like this...

[eluser]tusukgigi[/eluser]
i wanna count the same field
like this

indonesia(2)
-jakarta
-bandung

jepang(2)
-tokyo
-okinawa


but i got error...
Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource

$sql = "select city.city_name, count(city.city_name) AS t district.district_name from city join district
on city.district_id = district.id WHERE city.district_id = district.id order by district.district_name asc,
city.city_name asc";