Question

This works

SELECT DISTINCT  b.b_id 
FROM             b INNER JOIN c 
ON               b.b_id=c.b_id  
WHERE            c.active='yes' AND b.featured='no'

When the results should be 0 rows returned, this returns a null row with count = 0

SELECT DISTINCT  b.b_id, COUNT(c.c_id) AS count
FROM             b INNER JOIN c 
ON               b.b_id=c.b_id  
WHERE            c.active='yes' AND b.featured='no'

Am I doing something wrong?

Answer 1

I think you want a left join instead of an inner join since you want to return a count of 0 instead of a missing row when there is no matching c record for a given b record.

Also, you should include a group by when using an aggregate function, such as count.

SELECT
    b.b_id,
    COUNT(DISTINCT c.c_id) AS count
FROM 
    b 
    LEFT JOIN c 
        ON b.b_id=c.b_id  
        AND c.active='yes' 
WHERE b.featured='no'
GROUP BY b.b_id