Removing rows on outer query when subquery returns null

Question

After the select is executed, I am getting the error "unknown column 'points' in 'where clause'

How can I remove rows from the outer query that contain null records returned from a sub-query? (I need to use the sub-query, as I have another bunch of sub-queries that need to be run to return results I am after)

SELECT  
   s.student_name_first,
   s.student_name_last,
   (
   SELECT sum(i.points)
   FROM incidents i
   WHERE i.student = s.id
   ) AS points
FROM students s
WHERE points IS NOT NULL
GROUP BY s.id

I have also tried, with the same results

SELECT  
   s.student_name_first,
   s.student_name_last,
   (
   SELECT sum(i.points) AS points
   FROM incidents i
   WHERE i.student = s.id AND points IS NOT NULL 
   ) AS p
FROM students s
GROUP BY s.id

thanks in advance

---

Solution:

What I was looking for was HAVING

SELECT  
   s.student_name_first,
   s.student_name_last,
   (
   SELECT COALESCE(sum(i.incident_points),0)
   FROM incidents i
   WHERE i.student = s.id
   ) as points
FROM students s
GROUP BY s.id
HAVING points > 0

Answer 1

The problem is that you can't use SELECT aliases in the WHERE clause, they have to be in HAVING .

But if you use an inner join, you won't get any null rows in the first place.

SELECT s.student_name_first,
       s.student_name_last,
       SUM(i.points) AS points
FROM students s
JOIN incidents i
ON i.student = s.id
GROUP BY s.id