[Mapserver-users] Classes based on Postgis && function

[Jan Hartmann]

Benjamin,

You can use named computed variables in PostgreSQL:

select table1.the_geom from
     ( select table1.the_geom,table2.the_geom, table1.oid
         case when table1.fieldX = 'x' then 1
              when table1.the_geom && table2.the_geom then 2
         end as myclass
         from table1,table2
         where table1.id = table2.id
     ) as foo using unique=table1.oid using srid=...

after which you can use the new computed variable "myclass" as a regular 
MapServer CLASSITEM. The computed values of this variable go into the 
EXPRESSION statement:

CLASSITEM myclass
CLASS
    EXPRESSION 1
    COLOR ...
    ...
END
CLASS
    EXPRESSION 2
    COLOR ...
    ...
END

Jan

Benjamin Wragg wrote:
> Hi guys,
>  
> Does anyone know if its possible to have a layer with two classes, one 
> with a simple SQL expression and the other with a SQL statement that 
> uses a PostGIS spatial function. Something like the following logic:
>  
> class 1 = where table1.fieldX = 'x'
> class 2 = where table1.fieldX = 'x' and table1.the_geom && 
> table2.the_geom and table2.fieldY='Y'
>  
> I can do it in two layers, but is it possible in one layer with two classes?
>  
> Cheers,
>  
> Benjamin

Jan Hartmann
Department of Geography
University of Amsterdam
jhart at frw.uva.nl