11

Note: This question was published at Stackoverflow at first.

I have a geometry table points_table with SRID 4326 and a few points in it.

I need to find a distance between a pair of points (features) from this table.

I would like to select one point with id = X and another point with id = Y and then find a distance between them with ST_Distance function.

I know how to query these two points from the database:

select * from points_table where id = X or id = Y;

But this query returns a result, which I do not know how to pass to ST_Distance, because ST_Distance takes 2 parameters.

I have tried Select ST_Distance(select the_geom from points_table where id = X or id = Y);

But it is obviously wrong.

How can I find the distance between two geometry points (features) from a table?

P.S. All the examples I have found so far show the ST_Distance usage with points hardcoded into the arguments of the ST_Distance function. I have not found an example, where ST_Distance is used to calculate a distance between two points from the same table.

25

You need to reference your table twice, giving it different aliases:

SELECT ST_Distance(a.geom, b.geom)
FROM points_table a, points_table b
WHERE a.id='x' AND b.id='y';

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.