Querying data linked to a postGIS database

Question

My project is coming along nicely! A brief background on my project. I have a world map that is colored to show the country of origin of the students at a college. Each color represents the number students (a range). E.g. any country colored red has 1 to 20 students at the college. When you click on a country, I was successful in displaying data specific to that country in a pop-up.

Hopefully I can describe what I want to do next.... I want to add the ability to query the map such that the countries that satisfy the query will be highlighted on the map.
So for example, in my html form I enter > 300... click on submit.... England, India and USA are highlighted. I've figured out that I need to use WFS getFeature but as you can see it's the how that I need help with...

Can anyone direct me to an example of the above or give me some suggestions, I would be most appreciative.

I am using MapSever, PostGIS and Openlayers

Chris

Answer 1

Maybe "Drawing selected features in Mapserver with mapscript" can get you started.

Mapserver's Querymap feature seems to be another way to go.

Answer 2

I don't know how to do it through a wms-service, but Mapserver has the ability to both handle a custom sql-query for getting the data (take a look at the third and fourth example here)

, and you can use run-time substitution to insert some value from the client into that query. I remember I struggled some to get it working because I missed the validation against the datapattern. You can read about that here.

HTH Nicklas