Column does not exist error when using Having clause

I’m following along the steps in this article and am having trouble with the following query:

SELECT Quantity, COUNT(*) AS Quantity_Counts
FROM sqlbank3
WHERE UnitPrice >= 5
GROUP BY Quantity
HAVING Quantity_Counts < 450
ORDER BY Quantity_Counts DESC
LIMIT 10;

ERROR: column "quantity_counts" does not exist

LINE 5: HAVING Quantity_Counts < 450

I put everything in lower case to see if that did anything but to no avail. I have created Quantity as an integer. The query runs when I remove the HAVING clause so it’s certainly finding the Quantity_Counts column, just not with the HAVING clause.
Any help is appreciated.

>Solution :

The HAVING clause is supposed to be evaluated before the SELECT clause. You cannot use the alias defined in SELECT in HAVING for that reason.

You must use

HAVING COUNT(*) < 450

instead.

(Some DBMS allow it to use alias names in the HAVINGclause, though.)