mysql - Geo SQL to find points near location -


i using below sql:

based on http://www.scribd.com/doc/2569355/geo-distance-search-with-mysql

select * , 3956 *2 * asin( sqrt( power( sin( ( - 36.8812573 - abs( stop_lat ) ) * pi( ) /180 /2 ) , 2 ) + cos( - 36.8812573 * pi( ) /180 ) * cos( abs( stop_lat ) * pi( ) /180 ) * power( sin( ( 174.63832160000004 - stop_lon ) * pi( ) /180 /2 ) , 2 ) ) ) distance stops having distance <100 limit 0 , 30

to find stops within radius of current lat , lon.

i using gtfs data , schema below. (the lat , lon , last 2 columns)

01  7106    210 victoria st     -36.8481990     174.7544900 0002    7108    220 victoria st     -36.8481710     174.7523800 0003    7110    36 college hill     -36.8485220     174.7485400 0004    7112    68 college hill     -36.8479760     174.7466700 0005    7114    2 jervois rd    -36.8471670     174.7437800 0006    7116    90 jervois rd   -36.8453760     174.7408300 0007    7118    160 jervois rd  -36.8453250     174.7373100 0008    7120    206 jervois rd  -36.8454990     174.7354500 0009    7122    270 jervois rd  -36.8474010     174.7321400 0012    7121    203 jervois rd  -36.8473770     174.7319200 0013    7119    165 jervois rd  -36.8454100     174.7348400

the table structure this:

enter image description here

as far can see, query should return results. doesn't. can tell me might missing?

*** update ***********

i noticed missing temp output table name, getting results. however, start @ 5000 distance location. ideas?

updated sql:

select * , 3956 *2 * asin( sqrt( power( sin( ( - 36.8812573 - abs( stop_lat ) ) * pi( ) /180 /2 ) , 2 ) + cos( - 36.8812573 * pi( ) /180 ) * cos( abs( stop_lat ) * pi( ) /180 ) * power( sin( ( 174.63832160000004 - stop_lon ) * pi( ) /180 /2 ) , 2 ) ) ) distance stops dest having distance <5100 order distance limit 10

thanks,

i suspect formula culprit. if took reliable source , made no errors in implementing, there can e.g. unit confusion.

  • there's error: abs never needed, there's no such thing in the ‘haversine’ formula. in 2nd case, doesn't change cos function, in 1st case, does.

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