For ensuring there are no cloud occurences in a given roi I used
except at first then realised "having" combined with count/groupby was
the key.
Having 0 occurence or in our case having maximum pixels clear - same
either way.
These queries get thorny - sqlalchemy orm made things alot easier for
us becauses chances are that your having subquery needs to be joined
to something for additional criteria.
On 10/06/2010, at 5:02 AM, Mike Toews <[email protected]> wrote:
You could also use the EXCEPT set operator:
SELECT * FROM tbl_nla
EXCEPT
SELECT * FROM tbl_nla
JOIN tbl_rvb ON ST_DWithin(tbl_nla.the_geom, tbl_rvb.the_geom, 100);
-Mike
On 9 June 2010 11:19, Paul Ramsey <[email protected]> wrote:
That's actually a surprisingly tricky question (to solve
efficiently).
The approach I have usually used is the counterintuitive one: do a
left join on the positive constraint (*is* within 100 meters) and the
return the rows that did *not* match the join (and therefore have
null
unique id values in the resultant).
SELECT tbl_nla.gid FROM
tbl_nla LEFT JOIN tbl_rvb
ON ST_DWithin(tbl_nla.the_geom, tbl_rvb.the_geom, 100)
WHERE tbl_rvb.gid IS NULL;
P.
On Wed, Jun 9, 2010 at 2:06 PM, G. van Es <[email protected]> wrote:
I have two tables. tbl_nla has points as geometry and tbl_rvb has
multipolygons.
We want to list all the points of tbl_nla with no objects of
tbl_rvb within 100 metres.
Can anyone point me in the right direction?
Thanks,
Ge
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