对于ST_Distance函数

Question

此SQL生成以下内容：

SELECT city FROM travel_logs ORDER BY ST_Distance(travel_logs.start_point, ST_GeographyFromText('SRID=4326;POINT(101.652506 3.167610)')) 

"Tshopo"
"Tshopo"
"Mongala"
"Haut-Komo"

此SQL生成以下内容：

SELECT city, count(*) AS count FROM travel_logs GROUP BY travel_logs.start_point, city ORDER BY ST_Distance(travel_logs.start_point, ST_GeographyFromText('SRID=4326;POINT(101.652506 3.167610)')) 

"Tshopo";1
"Tshopo";1
"Mongala";1
"Haut-Komo";1

基本上，我想要这样的结果，按城市分组和同一城市的次数。像这样的东西

"Tshopo";2  <--- its summed up correctly
"Mongala";1
"Haut-Komo";1

我不是加入，子查询的专家，会有帮助吗？提前谢谢。

Answer 1

这对我有用：

select city, count(*) as count
from
(SELECT city FROM travel_logs ORDER BY ST_Distance(travel_logs.start_point, ST_GeographyFromText('SRID=4326;POINT(101.652506 3.167610)'))
) as subquery_travel_logs_nearest group by city

Answer 2

没有子查询的简单，纯SQL：

SELECT city, count(*)
FROM travel_logs
GROUP BY city
ORDER BY ST_Distance(start_point,
         ST_GeographyFromText('SRID=4326;POINT(101.652506 3.167610)'));