gambrels

Select Largest Polygon in each parcel

Discussion created by gambrels on Nov 8, 2010
Latest reply on Nov 9, 2010 by gambrels
Hi all,

I am trying to identify the largest building in each of my parcels, so that I can join the parcel's address with the building footprint.  I am going on the assumption that the largest building in an urban setting is usually the primary structure, though I'm sure there are instances where this is not true.

So, I am attempting to do this as in an older forum post I found, But I can't get the reccommendations to work:
http://forums.esri.com/thread.asp?c=93&f=982&t=302006

- I am using ArcInfo 9.3.1.
- I have a parcels Feature Class in which each feature has a single ID and each ID has only one feature.
- I have a buildings Feature Class which I intersected with the parcels to accommodate cases where buildings overlapped parcel lines.
- I did a "One-to-Many" spatial join so that now each building on a parcel includes the host parcel's attributes.

So it seems that now I just need to write a SQL query which will look at all buildings with identical PARCEL id's and then select the one with the largest BUILDING area.  Here's what I have input in the 'Select by Attributes' dialog:

SELECT * FROM BldgsToCompare WHERE:
-----------------------------------------------------------------------------------
"BLDG_AREA" in (select max("BLDG_AREA") from BldgsToCompare group by "TAX_ACCT")
-----------------------------------------------------------------------------------

"BLDG_AREA" is the square footage of each building
"TAX_ACCT" is the unique identifier for each parcel
"BldgsToCompare" is the Feature Class resulting from the Spatial Join. 

Any help would be much appreciated!

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