How can I count how many buffers intersects and select only those which have between 2 AND 6 intersections with other buffers? I can create a buffer with following query, but I don't have an idea on how to count intersections
SELECT ST_Buffer(geom::geography, 400)
FROM mytable;
I appreciate any help. Thanks.
It is wrong to use a buffer in such case, as the buffer is only an approximation. Instead, use the index compatible st_dwithin() function.
The idea is to select all points (polygons or else) that are within twice the distance, to group the result and keep the ones having at least 6 nearby features.
The example below use 2 tables, but you can use the same table twice.
SELECT myTable.ID, count(*), array_agg(myOtherTable.ID) as nearby_ids
FROM mytable
JOIN myOtherTable ON st_Dwithin(mytable.geom::geography, myOtherTable.geom::geography, 800)
GROUP BY myTable.ID
HAVING count(*) >= 6;
To use the same table twice, you can alias them:
SELECT a.ID, count(*), array_agg(b.ID) as nearby_ids
FROM mytable a
JOIN mytable b ON st_Dwithin(a.geom::geography, b.geom::geography, 800)
GROUP BY a.ID
HAVING count(*) >= 6;
Related
I have created the following query:
select t.id, t.row_id, t.content, t.location, t.retweet_count, t.favorite_count, t.happened_at,
a.id, a.screen_name, a.name, a.description, a.followers_count, a.friends_count, a.statuses_count,
c.id, c.code, c.name,
t.parent_id
from tweets t
join accounts a on a.id = t.author_id
left outer join countries c on c.id = t.country_id
where t.row_id > %s
-- order by t.row_id
limit 100
Where %s is a number that starts at 0 and is incremented by 100 after each such query is conducted. I want to fetch all records from the database using this method, where I just increase the %s in the where condition. I found this approach on https://ivopereira.net/efficient-pagination-dont-use-offset-limit. I also included a column in my table which is corresponding to row number (I named it row_id). Now the problem is when I run this query the first time, it returns rows which have an row_id of 3 million. I would like the cursor (not sure if my terminology is correct) to start from rows with row_id 1 through 100 and so on. The table contains 7 million rows. Am I missing something obvious with which I could achieve my goal?
I have hundreds of polygon (circles) where some of the polygon intersected with each others. This polygon is come from single feature layer. What I am trying to do is to delete the intersected circles.
It is similar to this question: link, but those were using two different layer. In my case the intersection is from single feature layers.
If I understood your question right, you just need to either create a CTE or simple subquery.
This might give you a good idea of how to solve your issue:
CREATE TABLE t (id INTEGER, geom GEOMETRY);
INSERT INTO t VALUES
(1,'POLYGON((-4.54 54.30,-4.46 54.30,-4.46 54.29,-4.54 54.29,-4.54 54.30))'),
(2,'POLYGON((-4.66 54.16,-4.56 54.16,-4.56 54.14,-4.66 54.14,-4.66 54.16))'),
(3,'POLYGON((-4.60 54.19,-4.57 54.19,-4.57 54.15,-4.60 54.15,-4.60 54.19))'),
(4,'POLYGON((-4.40 54.40,-4.36 54.40,-4.36 54.38,-4.40 54.38,-4.40 54.40))');
This data set contains 4 polygons in total and two of them overlap, as seen in the following picture:
Applying a CTE with a subquery might give you what you want, which is the non-overlapping polygons from the same table:
SELECT id, ST_AsText(geom) FROM t
WHERE id NOT IN (
WITH j AS (SELECT * FROM t)
SELECT j.id
FROM j
JOIN t ON t.id <> j.id
WHERE ST_Intersects(j.geom,t.geom)
);
id | st_astext
----+---------------------------------------------------------------------
1 | POLYGON((-4.54 54.3,-4.46 54.3,-4.46 54.29,-4.54 54.29,-4.54 54.3))
4 | POLYGON((-4.4 54.4,-4.36 54.4,-4.36 54.38,-4.4 54.38,-4.4 54.4))
(2 rows)
You can write quite clear delete statement using EXISTS clause. You literally want to delete the rows, for which there exists other rows which geometry intersects:
DELETE
FROM myTable t1
WHERE EXISTS (SELECT 1 FROM myTable t2 WHERE t2.id <> t1.id AND ST_Intersects(t1.geom, t2.geom))
Using ms-sql 2008 r2; am sure this is very straightforward. I am trying to identify where a unique value {ISIN} has been linked to more than 1 Identifier. An example output would be:
isin entity_id
XS0276697439 000BYT-E
XS0276697439 000BYV-E
This is actually an error and I want to look for other instances where there may be more than one entity_id linked to a unique ISIN.
This is my current working but it's obviously not correct:
select isin, entity_id from edm_security_entity_map
where isin is not null
--and isin = ('XS0276697439')
group by isin, entity_id
having COUNT(entity_id) > 1
order by isin asc
Thanks for your help.
Elliot,
I don't have a copy of SQL in front of me right now, so apologies if my syntax isn't spot on.
I'd start by finding the duplicates:
select
x.isin
,count(*)
from edm_security_entity_map as x
group by x.isin
having count(*) > 1
Then join that back to the full table to find where those duplicates come from:
;with DuplicateList as
(
select
x.isin
--,count(*) -- not used elsewhere
from edm_security_entity_map as x
group by x.isin
having count(*) > 1
)
select
map.isin
,map.entity_id
from edm_security_entity_map as map
inner join DuplicateList as dup
on dup.isin = map.isin;
HTH,
Michael
So you're saying that if isin-1 has a row for both entity-1 and entity-2 that's an error but isin-3, say, linked to entity-3 in two separe rows is OK? The ugly-but-readable solution to that is to pre-pend another CTE on the previous solution
;with UniqueValues as
(select distinct
y.isin
,y.entity_id
from edm_security_entity_map as y
)
,DuplicateList as
(
select
x.isin
--,count(*) -- not used elsewhere
from UniqueValues as x
group by x.isin
having count(*) > 1
)
select
map.isin
,map.entity_id
from edm_security_entity_map as map -- or from UniqueValues, depening on your objective.
inner join DuplicateList as dup
on dup.isin = map.isin;
There are better solutions with additional GROUP BY clauses in the final query. If this is going into production I'd be recommending that. Or if your table has a bajillion rows. If you just need to do some analysis the above should suffice, I hope.
The query below returns 9,817 records. Now, I want to SELECT one more field from another table. See the 2 lines that are commented out, where I've simply selected this additional field and added a JOIN statement to bind this new columns. With these lines added, the query now returns 649,200 records and I can't figure out why! I guess something is wrong with my WHERE criteria in conjunction with the JOIN statement. Please help, thanks.
SELECT DISTINCT dbo.IMPORT_DOCUMENTS.ITEMID, BEGDOC, BATCHID
--, dbo.CATEGORY_COLLECTION_CATEGORY_RESULTS.CATEGORY_ID
FROM IMPORT_DOCUMENTS
--JOIN dbo.CATEGORY_COLLECTION_CATEGORY_RESULTS ON
dbo.CATEGORY_COLLECTION_CATEGORY_RESULTS.ITEMID = dbo.IMPORT_DOCUMENTS.ITEMID
WHERE (BATCHID LIKE 'IC0%' OR BATCHID LIKE 'LP0%')
AND dbo.IMPORT_DOCUMENTS.ITEMID IN
(SELECT dbo.CATEGORY_COLLECTION_CATEGORY_RESULTS.ITEMID FROM
CATEGORY_COLLECTION_CATEGORY_RESULTS
WHERE SCORE >= .7 AND SCORE <= .75 AND CATEGORY_ID IN(
SELECT CATEGORY_ID FROM CATEGORY_COLLECTION_CATS WHERE COLLECTION_ID IN (11,16))
AND Sample_Id > 0)
AND dbo.IMPORT_DOCUMENTS.ITEMID NOT IN
(SELECT ASSIGNMENT_FOLDER_DOCUMENTS.Item_Id FROM ASSIGNMENT_FOLDER_DOCUMENTS)
One possible reason is because one of your tables contains data at lower level, lower than your join key. For example, there may be multiple records per item id. The same item id is repeated X number of times. I would fix the query like the below. Without data knowledge, Try running the below modified query.... If output is not what you're looking for, convert it into SELECT Within a Select...
Hope this helps....
Try this SQL: SELECT DISTINCT a.ITEMID, a.BEGDOC, a.BATCHID, b.CATEGORY_ID FROM IMPORT_DOCUMENTS a JOIN (SELECT DISTINCT ITEMID FROM CATEGORY_COLLECTION_CATEGORY_RESULTS WHERE SCORE >= .7 AND SCORE <= .75 AND CATEGORY_ID IN (SELECT DISTINCT CATEGORY_ID FROM CATEGORY_COLLECTION_CATS WHERE COLLECTION_ID IN (11,16)) AND Sample_Id > 0) B ON a.ITEMID =b.ITEMID WHERE a.(a.BATCHID LIKE 'IC0%' OR a.BATCHID LIKE 'LP0%') AND a.ITEMID NOT IN (SELECT DIDTINCT Item_Id FROM ASSIGNMENT_FOLDER_DOCUMENTS)
In a table I have records with id's 2,4,5,8. How can I receive a list with values 1,3,6,7. I have tried in this way
SELECT t1.id + 1
FROM table t1
WHERE NOT EXISTS (
SELECT *
FROM table t2
WHERE t2.id = t1.id + 1
)
but it's not working correctly. It doesn't bring all available positions.
Is it possible without another table?
You can get all the missing ID's from a recursive CTE, like this:
with recursive numbers as (
select 1 number
from rdb$database
union all
select number+1
from rdb$database
join numbers on numbers.number < 1024
)
select n.number
from numbers n
where not exists (select 1
from table t
where t.id = n.number)
the number < 1024 condition in my example limit the query to the max 1024 recursion depth. After that, the query will end with an error. If you need more than 1024 consecutive ID's you have either run the query multiple times adjusting the interval of numbers generated or think in a different query that produces consecutive numbers without reaching that level of recursion, which is not too difficult to write.