Querying and displaying sid files through php-mapscript

[Volkan Ulukut]

Hey list,
I've been working on a street map and when I begun to add a search function
for it I bumped into the question how I could get the City-District-Street
relation from sid file and show it to user so the user can choose where he
wants to find step by step. 
Suppose I got a sid file named street.sid and these are the fields:
City | DistrictName | StreetName
I show this sid file on the map with street being the label. 
Now what I wish to do is putting 2 combobox' under advanced search and one
of them would have the city names the other the district names. So when the
user looks for a street in the city C and District D he could choose from
comboboxes and type its name on the search field. It would be fairly easy if
City - District - Street relation was in a table on mysql. But only data I
got is this street.sid. My question is Can I get the Citynames,
Districtnames and streetnames from the sid file into my php application?
Hope I could be clear enough. Thanks in advance.