New answers tagged sql
3
If you use the PostGIS function st_equals instead of the = operator, the query planner will be able to use the geometry index and work more efficiently.
You can check if that's actually happening by checking the query plan using the EXPLAIN command before your query.
0
I'll try to give an answer that covers generally your issue.
So let's say you have a table of points called "clients" and another table called "stores" for store.
one of the issue is to know how you get your geometry that symbolized the road,
you will need to use some routing here to get a "real" road trajectory based on a road network, and then retrieve ...
-1
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So, I invite everyone to fly with me in a plane with the engine I have assembled with the name: "Free and Magic geoSQL", in order to admire the beautiful mountain scenery of the Cordillera mountain system and from a height of flight to see ...
1
Here's a quick Java translation of the OS visual basic code from the spread sheet mentioned in the comments.
import org.locationtech.jts.geom.Coordinate;
import org.locationtech.jts.geom.GeometryFactory;
import org.locationtech.jts.geom.Point;
public class OSGridref {
static GeometryFactory GF = new GeometryFactory();
static String[][] gridLetters = { {...
0
The OSGB national grid uses nested 5x5 squares and two sets of digits to provide a location (see https://en.wikipedia.org/wiki/Ordnance_Survey_National_Grid#Grid_digits):
For example, the grid reference of the 100 m square containing the summit of
Ben Nevis is NN 166 712. (Grid references may be written with or without spaces;
e.g., also NN166712.) NN has ...
-1
Have you tried any tool which converts your coordinates? Here you have an example: https://www.asturnatura.com/sinflac/calculadora-conversiones-coordenadas.php
Good luck.
0
You can try to compute the kernel density of your points with this function: https://gist.github.com/AbelVM/dc86f01fbda7ba24b5091a7f9b48d2ee
And after you can use this density to mitigate the K, so you would need a higher K to be displayed in a region with a lot of points.
Be aware that if you do that, multiple points can be shown even if they are close ...
0
For anyone landing here searching for a reason why the left() function doesn't work in arcgis, this is what I found:
LEFT() and RIGHT() don't work for fgdb's. You must use SUBSTRING(field FROM start for NumChars)
The correct syntax for the SUBSTRING function is:
SUBSTRING("Field" FROM 1 FOR 3)
- this example returns everything from the first char to the ...
2
Try to specify No geometry for the geometry type.
0
You can achieve that using an SQL Query in the DB Manager of QGIS.
You choose Database / Database Manager / Database Manager then Virtual Layers / Qgis Layers you can then try queries like the following :
select zone, direction, count (*) as total from my_table
group by zone
having total>1
The result will show all zones having more than one direction (=...
2
First of all, the trigger should be on buffer table. Secondly, you should insert the intersection (now you claculate it but then leave it behind).
I used the following codes to create 3 tables:
create table buffer (id serial primary key );
select addgeometrycolumn('buffer', 'geom' , 3979 ,
'POLYGON' , 2);
create table polygons (id serial primary key );
...
0
if you're using javascript, you can create a query from your feature layer https://developers.arcgis.com/javascript/latest/api-reference/esri-layers-FeatureLayer.html#createQuery
var layer = new FeatureLayer({
url: "https://baseURL/myMapServer/0"
});
var queryParams = layer.createQuery();
queryParams.where = "category = 'cat1'";
layer.queryFeatures(...
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