Where condition in GROUP_CONCAT

Question

I'm trying to get the Image IDs in which the label 'car' is not present. I've tried to group all the object labels which is related to specific Image ID.

I'm trying to exclude the Image ID in which the 'car' is present. But instead of this only object label 'car' is getting excluded in the group.

I've tried this -

SELECT used_car_image_id, GROUP_CONCAT(DISTINCT object_label ORDER BY object_label ASC SEPARATOR ',')
FROM individual_used_cars_image_label 
GROUP BY used_car_image_id
HAVING GROUP_CONCAT(DISTINCT object_label ORDER BY object_label ASC SEPARATOR ',') != 'car'

And this -

SELECT used_car_image_id, GROUP_CONCAT(DISTINCT object_label ORDER BY object_label ASC SEPARATOR ',')
FROM individual_used_cars_image_label 
WHERE object_label !='car'
GROUP BY used_car_image_id

Both queries are giving the ID and just excluding the object label 'car'. The output should be the row of Image IDs in which there's no object label named 'car'

Answer 1

You could just add a count of how many of the object_label values associated with each used_car_image_id were equal to car and use that to filter the results. This query takes advantage of the fact that MySQL treats boolean expressions as 1 (true) or 0 (false) in a numeric context.

SELECT used_car_image_id, GROUP_CONCAT(DISTINCT object_label ORDER BY object_label ASC SEPARATOR ',')
FROM individual_used_cars_image_label 
GROUP BY used_car_image_id
HAVING SUM(object_label = 'car') = 0

Demo on dbfiddle

Answer 2

You should be using a CASE expression in the HAVING clause which checks for the presence of car :

SELECT used_car_image_id, GROUP_CONCAT(DISTINCT object_label ORDER BY object_label SEPARATOR ',') labels
FROM individual_used_cars_image_label 
GROUP BY used_car_image_id
HAVING COUNT(CASE WHEN object_label = 'car' THEN 1 END) = 0;

Answer 3

You can easily exclude the Image IDs with label 'car' with NOT EXISTS:

SELECT 
  t.used_car_image_id, 
  GROUP_CONCAT(DISTINCT t.object_label ORDER BY t.object_label ASC SEPARATOR ',') labels
FROM individual_used_cars_image_label t 
WHERE NOT EXISTS (
  SELECT 1 FROM individual_used_cars_image_label
  WHERE used_car_image_id = t.used_car_image_id AND object_label ='car' 
)
GROUP BY t.used_car_image_id