PostgreSQL Where clause using calculated distance - postgresql

Question

I have a PostgreSQL query that looks like this:
SELECT *,
2 * 3961 * asin(sqrt((sin(radians((latitude - 40.2817993164062) / 2))) ^ 2 + cos(radians(40.2817993164062)) * cos(radians(latitude)) * (sin(radians((longitude - -111.720901489258) / 2))) ^ 2)) as distance,
(SELECT json_agg(deals.*) FROM deals WHERE vendors.id = deals.vendorid) as deals FROM vendors
WHERE ( category = 'Food' )
AND (distance < 80)
AND (nationwide IS FALSE OR nationwide is NULL)
ORDER BY featured ASC, created DESC, distance ASC
I'm getting the distance in miles using the second select part.
The problem is the part that says AND (distance < 80) I get the following error: column "distance" does not exist the weird thing is that if I remove the AND (distance < 80) it works and it also sorts correctly by distance, also the outputted data includes distance, so it's grabbing the distance correctly but for some reason wont let me use the distance as a filter in the WHERE clauses and I can't figure out why.

Answer 1

distance is just an alias. You could try something like:
WITH vendors_distance as (
SELECT *,
2 * 3961 * asin(sqrt((sin(radians((latitude - 40.2817993164062) / 2))) ^ 2 + cos(radians(40.2817993164062)) * cos(radians(latitude)) * (sin(radians((longitude - -111.720901489258) / 2))) ^ 2)) as distance
FROM vendors
WHERE ( category = 'Food' )
AND (nationwide IS FALSE OR nationwide is NULL)
)
SELECT vendors_distance.*,
(SELECT json_agg(deals.*) FROM deals WHERE vendors_distance.id = deals.vendorid) as deals
FROM vendors_distance
WHERE (distance < 80)
ORDER BY featured ASC, created DESC, distance ASC