MySQL Forums :: PHP :: multiquery or php postprocessing

Hi,
I need to get some records from a mysql table by php.
Once I have the records I need to get each single field and perform a grouping operation to suppress duplicates.
What's the best way for perfomance?
1) perform one query for each field (with the same FROM...WHERE statement) perfoming the grouping in the query
2) perform one single query and get the fielde for grouping managing the php result array


The table:

Cities Streets
new york firstStreet
new york secondStreet
s.francisco firstStreet


What I need:

Cities
new york
s.francisco


Streets
firstStreet
secondStreet


Thanks!!!