John, look: http://mapserver.gis.umn.edu/docs/reference/phpmapscript-class/classes/layerobj for the function queryByAttributes in PHP/Mapscript. The function accept the 'qstring' parameter, a Mapserver expression (http://mapserver.gis.umn.edu/docs/howto/msexpressions), but not a SQL query. It can be hard to create with PHP a 'unique value' response to popolate the combo. I believe the better way to do this is to store the shapefiles in a db, like PotgreSQL/PostGIS (http://www.postgresql.org/ & http://www.postgis.org/) and query it with the clause 'GROUP BY' on the fields you want.
If you are in trouble with postgres let me know bye ..........................pg Pietro Giannini Bytewise srl - Area GIS 41°50'38.58"N 12°29'13.39"E > The documentation for PHP/Mapscript shows that it is possible to query > by attributes using "queryByAttributes" but I must supply the qstring to > get a match. Does anyone know of a way to get a list of unique values > for a given field ? > > What I want to do is populate a "select" control (aka combo box) on a > form with the unique values from a field in a shapefile. I'm > essentially building a query form for attribute data that is stored in > shapefiles. > > It seems like this shouldn't be too difficult but I'm coming into this > with a GIS background and am relatively new to php and mapserver. Any > help will be appreciated. > > J.B. > -- > --------------------------------------------- > John B. Churchill, M.S. > http://alx.al.umces.edu/~jchurch/ > GIS Specialist (301) 689-7109 > > University of Maryland Center for Environmental Science > Appalachian Laboratory http://www.al.umces.edu/ > Environmental Science Education http://alese.al.umces.edu/ > > 301 Braddock Road > Frostburg, MD 21532 > FAX - (301) 689-7200 >
