Question

I’m using the following query which returns the result as below:

SELECT  subnets.subnet_id , INET_NTOA(  subnets.address ) AS inet_address, subnet_masks.hosts, COUNT(addresses.STATUS) AS status_count
FROM subnets
LEFT JOIN subnet_masks ON subnets.mask_id = subnet_masks.mask_id
LEFT JOIN addresses ON subnets.subnet_id = addresses.subnet_id
WHERE addresses.status = 'allocated'
GROUP BY subnet_id      
ORDER BY subnets.address



subnet_id   inet_address    hosts   status_count
91          10.10.10.0      65534   3
71          192.168.1.0     254     6
90          192.168.10.0    254     1

However I want it return the rows that count 0 too, much like this:

subnet_id   inet_address    hosts   status_count
91          10.10.10.0      65534   3
76          172.128.0.0     254     0
71          192.168.1.0     254     6
90          192.168.10.0    254     1

I read that it may be a problem with my JOINs so I’ve tried a number of different ones and I’m getting the same result. Does anyone know what I’m doing wrong?

Answer 1

Your WHERE clause is filtering out records… move it to your LEFT JOIN to resolve the issue:

SELECT  subnets.subnet_id , INET_NTOA(  subnets.address ) AS inet_address, subnet_masks.hosts, COUNT(addresses.STATUS) AS status_count
FROM subnets
LEFT JOIN subnet_masks ON subnets.mask_id = subnet_masks.mask_id
LEFT JOIN addresses ON subnets.subnet_id = addresses.subnet_id AND addresses.status = 'allocated'
GROUP BY subnet_id      
ORDER BY subnets.address