sql根据经纬度查找数据库中的最近点

找最近的点：

greatCircleDistance是clickhouse内的函数
clickhouse

select lon,
	lat
from
	hisdb.t_sea_geo
order by
	greatCircleDistance(cast (lon as float),
	cast (lat as float ),120,19.5)
limit 1

其他：
说明：
0.03 表示数据库中最小格点数据的分辨率（也就是间隔）
104.03844是传入的参数经度
30.994878是传入的参数纬度

select geocode
from
	(
	select
			geocode,
			ABS(lon-cast(104.03844 as Decimal(8, 4))) as lonAbs,
			ABS(lat-cast(30.994878 as Decimal(8, 4))) as latAbs
	from
			public.t_forecast_geo ) t
where 
			t.lonAbs <= cast(0.03 as Decimal(5, 2))
	and
                 t.latAbs <= cast(0.03 as Decimal(5, 2))
order by
				t.lonAbs,
				t.latAbs asc
limit 1