Distinct not working properly - mysql

Question

I've wrote a query with DISTINCT but I still get duplicate records returned.
SELECT DISTINCT
`cuisine_types`.`id`,
`cuisine_types`.`name`,
`cuisine_types`.`image`,
(
SELECT group_concat(`tagname` separator ', ')
FROM `cuisine_tags`
WHERE `cuisine_type` = `cuisine_types`.`id`
) AS tags,
(
3959 * acos( cos( radians(" . $dLat . ") ) * cos( radians( gps_lat ) ) * cos( radians( gps_lon ) - radians(" . $dLon . ") ) + sin( radians(" . $dLat . ") ) * sin( radians( gps_lat ) ) )
) AS distance
FROM `company`
LEFT JOIN `cuisine_types`
ON
`company`.`cuisine_type_id` = `cuisine_types`.`id`
HAVING
distance < " .$dMiles
When I try using the GROUP BY function my query isn't working properly.
When I use GROUP BY I place it above my HAVING:
GROUP BY `cuisine_types`.`name`
Examples:
When I use it with these values:
$dLat = '52.779716';
$dLon = '21.84803';
$iKm = '30';
It returns:
id = 1
name = Snackbar
image =
tags = Patat, Snacks
distance = 17.4713944772963
When I use $iKm with 3000 it returns this row as well:
id = 1
name = Snackbar
image =
tags = Patat, Snacks
distance = 722.407714147792
So I get two records.
When I use this with groupby and $iKm = 30; It returns nothing. With a value of 3000 it returns one row. But I have one record with a distance of 17 miles so thats below 30.

Answer 1

This should fix your problem, the issue was the distance calculation blocked the GROUP BY function. By putting the equation in the HAVING itself, the problem seemed to be fixed. Sorry I can't explain it in more detail.
SELECT
`cuisine_types`.`name`,
`cuisine_types`.`id`,
`cuisine_types`.`image`
`c`.`gps_lat` as lat,
`c`.`gps_lon` as lon,
(SELECT group_concat(`tagname` separator ', ') FROM `cuisine_tags` WHERE `cuisine_type`=`cuisine_types`.`id`) as tags FROM `company` as c LEFT JOIN `cuisine_types` ON c.`cuisine_type_id`
= `cuisine_types`.`id` GROUP BY `cuisine_types`.`name` HAVING ( 3959 * acos( cos( radians(52.779716) ) * cos( radians( lat ) ) * cos( radians( lon ) - radians(21.84803) ) + sin( radians(52.779716) ) * sin( radians( lat ) ) ) ) < 2000;