how to find percentage or area of overlapped area of a polygon

Question

In SQL Server 2008 R2 I have created some polygons. I have also selected which polygon is overlapping another one Now I want to know overlapped area or percentage.

For area I am trying following SQL

SELECT location.STArea()
FROM
  ( SELECT location.STIntersection(
           (SELECT LOCATION
            FROM TEST.dbo.cn_overlap_trn
            WHERE plot_no = '657065700016801' ) )
   FROM TEST.dbo.cn_overlap_trn
   WHERE plot_no ='657065700016701') ;

in above SQL

SELECT location.STIntersection(
       (SELECT LOCATION
        FROM TEST.dbo.cn_overlap_trn
        WHERE plot_no = '657065700016801' ) )
FROM TEST.dbo.cn_overlap_trn
WHERE plot_no ='657065700016701';

is running fine but when I add STArea() function it results an error

Msg 102, Level 15, State 1, Line 11
Incorrect syntax near ';'.

Answer 1

You need an Alias for your subquery say A and also to your functions specially in your inner query for example:

Select location.STArea() as Area from
(
    select 
    location.STIntersection(
        ( 
        select location from TEST.dbo.cn_overlap_trn where plot_no =  '657065700016801'
        )
                            ) as Intersection
    from TEST.dbo.cn_overlap_trn 
    where plot_no ='657065700016701'
) A ;