MySQL | 计数行 IF 0 然后返回

Question

I want to create a function which check if there a any locations within a certain distance from a waypoint. the function to calculate the distance is already working. I start with the query shown below.

select loc_id from wp where calc_distance(52.15819, 6.40726, wp.lat, wp.lon) <100;

This query wil result in several rows, the next step would be to count the amount of rows, why won't the query below result in a number?

select count(loc_id from wp where calc_distance(52.15819, 6.40726, wp.lat, wp.lon) <100);

Any thoughts?

Small side question: What wuold be perferred:

1. Ccreate this function within MySQL and only call it from within a javascript file.
2. Create this function within my js file and only read the mySQL table when the javascript function is called.

TIA

ABBOV

Answer 1

Syntax error is all. You need a closing parenthesis after loc_id

select count(loc_id) from wp where calc_distance(52.15819, 6.40726, wp.lat, wp.lon) <100;