sql - calculate distance live and order asc|desc -


so when start web app, server gets user geolocation , save variable (latitude/longitude) i've got database with: id, name, latitude, longitude

now want select entries database , order them distance

i know how calculate distance between coordinates, dont know how order things "live"

can guys give me hint how solve this?

you can specify distance calculation (say example (longitude + latitude) divided 42) in order by clause

select id, name, latitude, longitude, (longitude + latitude) / 42 distance   yourtable  order (longitude + latitude) / 42

however, because distance calculation more complex (longitude + latitude) / 42, might want consider ordering results based on ordinal of column in result set (i think databases support this). like.....

select id, name, latitude, longitude, /* insert distance calculation here */ distance   yourtable  order 5  -- column ordinals 1-based

you should note though there gotchas approach. example, if order of columns changed or columns added, order by ordinal must changed or see unexpected results. if order field name or calculation isn't issue.


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