Question

Quest

The query selects all the points beginning with “Vancouver” and are within a 5 minute area from the center of all locations beginning with “Vancouver”. For example, Vancouver South Fraser, Vancouver Fairview, and Vancouver Ballantree Place W have latitudes and longitudes within 5 minutes of their average latitude and longitude. The latitudes and longitudes are stored as (4915, 12311) integer pairs (meaning 49.15’N and 123.11’W).

SQL Code

The following SQL abomination does the trick:

SELECT
  NAME
FROM
 STATION
WHERE
      DISTRICT_ID = '110'
  AND NAME LIKE 'Vancouver%'
  AND LATITUDE BETWEEN
    (SELECT round((min(LATITUDE) + max(LATITUDE)) / 2)-5 FROM STATION WHERE DISTRICT_ID = '110' AND NAME LIKE 'Vancouver%')
    and
    (SELECT round((min(LATITUDE) + max(LATITUDE)) / 2)+5 FROM STATION WHERE DISTRICT_ID = '110' AND NAME LIKE 'Vancouver%')
  AND LONGITUDE BETWEEN
    (SELECT round((min(LONGITUDE) + max(LONGITUDE)) / 2)-5 FROM STATION WHERE DISTRICT_ID = '110' AND NAME LIKE 'Vancouver%')
    and
    (SELECT round((min(LONGITUDE) + max(LONGITUDE)) / 2)+5 FROM STATION WHERE DISTRICT_ID = '110' AND NAME LIKE 'Vancouver%')
ORDER BY
  LATITUDE

Question

How can this query be simplified to remove the redundancy, without using a view?

Restrictions

The database is MySQL, but ANSI SQL is always nice.

Thank you!

Answer 1

select 
  name
from 
  (select 
    round((min(LATITUDE) + max(LATITUDE)) / 2) as LATITUDE,
    round((min(LONGITUDE) + max(LONGITUDE)) / 2) as LONGITUDE
   from STATION 
   where DISTRICT_ID = '110' 
     AND NAME LIKE 'Vancouver%') AS center
  inner join STATION s
where
  s.DISTRICT_ID = '110' 
  and s.NAME like 'Vancouver%'
  and s.LATITUDE between center.LATITUDE - 5 and center.LATITUDE + 5
  and s.LONGITUDE between center.LONGITUDE - 5 and center.LONGITUDE + 5