Locate nearby locations based on latitude and longitude (LAT,LNG) (continued)

Original source: http://blog.163.com/ezy_dk/blog/static/166651492201221445753585/

Reference Web: A preliminary study of nearby location search

The following is a summary of your own SQL code

Declare @EARTH_RADIUS float
Set @EARTH_RADIUS = 6371000.00-Earth's radius

declare @lat float
declare @lng float
declare @dlng float
declare @dlat float
declare @distance int			--distance
set @distance =				--300 m C9/>set @lat =xx.xxxxx				-This is the central location
set @lng = xxx.xxxx				-central location

set @dlng  = 2 * ASIN (SIN (@distance /(2 * @EARTH_RADIUS))/cos (@lat))
Set @dlng = degrees (@dlng) 
Set @dlat =  300/@EARTH_RADIUS
set @dla t = degrees (@dlat) 

declare @lng1 float
declare @lng2 float
declare @lat1 float
declare @lat2  Float
Set @lat1 = @lat-@dlat-				-Longitude
Set @lat2 = @lat + @dlat-				-east longitude

Set @lng1 = @lng
Set @lng2 = @lng + @dlng				--Northern latitude 

Select @lat1, @lat2, @lng1, @lng2
select Lat,lng 
from WHERE 
	(Lat > @lat1 and Lat < @lat2)-	-longitude range
	and 
	(LNG > @lng1 and LNG < @lng2)--	latitude range

Common sense:
1, Longitude (Latitude), longitude is positive, longitude is negative;
2, Latitude (longitude), latitude is positive, latitude is negative;
Figures: