Calculate distance between geo points using sql oracle

Question

who know and can demonstrate how to calculate distance using Pythagoras theorem (SQL oracle). table:

station_id        station_geom
395               POINT(-121.906834244728 37.3608541552538)
378               POINT(-121.890799999237 37.3477445655325)
312               POINT(-121.901782 37.329732)

Desire output:

station_id_start  station_id_end    distance 
395               378               2,23682150368419

honestly, what I did wasn't too smart: I separate column station_geom in two separate columns and then calculate the distance between stations for ex. SELECT sqrt(power(37.3608541552538-37.3477445655325,2)+power(-121.890799999237-(-121.906834244728),2))*108 as P_Distance , I do hope there is a simple solution how to do it. Thank you

Answer 1

As pointed out in the comments, your answer is already complete if the condition is you have to use Pythagoras's theorem. Why you have that condition I have no idea as it means your answer will be an approximation and not a very good one if the distances are long or you're not near the equator.

The simple solution to get a correct result is to ensure that your geometry field has correct projection data and then use the built in distance function. https://docs.oracle.com/database/121/SPATL/sdo_geom-sdo_distance.htm#SPATL1117

EDIT: Based on your comments we can forget about Pythagorus and try to use the built in Oracle spatial functions (assuming they are installed).

You first need to convert the well-known text WKT data (that is the name for data that looks like your points do) into a geometry object and tell Oracle that the numbers are lat long. You do this using the function SDO_GEOMETRY like so:

SELECT station_id, SDO_GEOMETRY(station_geom,4326) as station_geom_oracle FROM your_table

I'd suggest you make this a new table in your DB so you only have to do the conversion once. You can then use the SDO_DISTANCE function to calculate distances between these geometries as required.