Check the number of rows in MySQL and if it is equal to 0,

I am working on developing a function to detect locations within a specific distance from a waypoint. The distance calculation function is already functional, and I have initiated the process with the query displayed below.

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

After executing this query, multiple rows are returned. However, when I attempt to count the number of rows using the query below, it does not yield the desired numerical output.

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

I am seeking insights into why this issue may be occurring.

On another note, I am contemplating whether it would be more appropriate to:

  1. Create this function within MySQL and only call it from a JavaScript file.
  2. Develop this function within my JavaScript file and access the MySQL table solely when the JavaScript function is invoked.

Thank you in advance.

ABBOV

Answer №1

It seems there is a syntax error in your code. Make sure to add a closing parenthesis after loc_id

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

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