Hello List,

I have a question about SQL syntax for the proportion sum function.  I
have a couple of polygon tables, one of airspace and the other of land
use.  I'm trying to calculate acreage of land use classes underneath the
airspace polygons.  What I need is the proportion sum of the area of
intersected land use polygons grouped by unique land use class.

I can do this query and select the SUM of the areas of intersected
polygons, but this includes the total area of polygons that are
intersected but extend out beyond the extents of the target polygon.  I
can use the proportion sum (of intersected area) in a table update
statement, and then run the SQL, but I'd really like to keep it in one
step and do the calculation right in the query.

It boils down to this question - can Proportion Sum be used in an SQL
select statement to obtain overlapped area?

As always, thanks for any tips.

Will Mitchell
GIS Manager
The Environmental Company, Inc.
Charlottesville, Virginia

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