Dear List

In the past I have found that if I adapt the following SQL query (received
from MI tech support) for different tables it would return the same results
as using the cookie cutter.  I have used this SQL query to find out the
exact areal coverage of many polygons within a particular polygon - in this
case Hampshire hedgerows within our AONB polygon.  Often, just to test the
query is still working, I check that the cookie cutter (in this case using
the AONB to cut the hedgerows layer) returns the same result as the query.
This time it is not returning the same result.  The SQL query is returning
34.1 ha and the cookie (using the statistics tool) returns 38.1 ha.  Here
follows the query:

Select: 1992___Hants_hedge.Area_hectare, sum ( proportionoverlap (AONB . obj
, 1992___Hants_hedge . obj ) * area ( obj , "hectare" ) )

>From table: AONB , 1992___Hants_hedge

Where: AONB . Obj intersects 1992___Hants_hedge . Obj

Hoping someone out there has some ideas about which method is the most
reliable?

Cheers

Jacqui Foskett




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